Polymerization catalyst for polyester, polyester produced with the same, and process for producing polyester

ABSTRACT

A polymerization catalyst for polyester production which contains neither a germanium compound nor an antimony compound as a major component. It contains aluminum as the main metallic ingredient, has excellent catalytic activity, and gives a polyester which is effectively inhibited from suffering thermal degradation, during melt molding, without deactivating or removing the catalyst, and is excellent in thermal stability, stability to thermal oxidation, and hydrolytic resistance. The polymerization catalyst contains as a first metallic ingredient at least one member selected among aluminum and compounds thereof and further contains a phosphorus compound represented by a specific chemical formula. The polyester produced with this catalyst is usable as fibers, films, sheets, various moldings including hollow moldings, etc.

TECHNICAL FIELD

[0001] This invention relates to a polymerization catalyst forpolyester, polyester produced by using the same and a process forproducing polyester, and in particular to a novel polyesterpolymerization catalyst not using a germanium or antimony compound as amajor catalytic component, polyester produced by using the same and aprocess for producing polyester. This invention provides fibers, films,sheets and hollow molded articles comprising polyester produced by thenovel polyester polymerization catalyst not using a germanium orantimony compound as a major catalytic component.

BACKGROUND ART

[0002] Polyesters represented by polyethylene terephthalate (PET),polybutylene terephthalate (PBT), polyethylene naphthalate (PEN) etc.are excellent in mechanical and chemical characteristics, and are usedin various fields for example in fibers for clothing and industrialmaterials, films for packaging or for magnetic tapes, sheets, bottlessuch as hollow molded articles, casings for electrical or electronicparts, and other molded articles of engineering plastics, depending onthe characteristics of each polyester.

[0003] As typical polyester, polyester comprising an aromaticdicarboxylic acid and an alkylene glycol as major constituentcomponents, for example polyethylene terephthalate (PET), isindustrially produced by esterification or transesterification ofterephthalic acid or dimethyl terephthalate and ethylene glycol toproduce bis(2-hydroxyethyl) terephthalate which is then subjected topolycondensation at high temperatures in vacuo in the presence of acatalyst.

[0004] As a conventional polyester polymerization catalyst used inpolycondensation of polyester, antimony trioxide has been used widely.Antimony trioxide is an inexpensive and highly active catalyst, but whenantimony trioxide is used as a major component, that is, when it is usedin such an amount as to exhibit a practical rate of polymerization, anantimony metal is precipitated at the time of polycondensation to causeproblems such as gray discoloration or formation of insoluble particlesin polyester. For this reason, polyester absolutely free of antimony orexcluding antimony as a major catalytic component is desired.

[0005] The above-described insoluble particles in polyester cause thefollowing problems:

[0006] (1) In polyester for film, the antimony metal precipitated servesas insoluble particles in polyester, which causes not only contaminationof an outlet during melt extrusion but also deficiency in the surface offilm. Further, when the polyester with insoluble particles is used as astarting material of hollow molded articles, it is difficult to obtainhollow molded articles excellent in transparency.

[0007] (2) The insoluble particles in polyester for fibers serves asinsoluble particles not only causing a reduction in the strength offibers, but also deposits around spinnerets during spinning. Inproduction of polyester fibers, a polyester polymerization catalyst notcausing formation of insoluble particles is desired from the viewpointof productivity.

[0008] As a method of solving the problem described above, an attempthad been made at preventing gray discoloration and formation ofinsoluble particles in PET while using antimony trioxide as a catalyst.In Japanese Patent No. 2666502, for example, formation of blackinsoluble particles in PET is prevented by using antimony trioxide, abismuth compound and a selenium compound as a polycondensation catalyst.Further, JP-A 9-291141 describes that precipitation of an antimony metalis prevented when antimony trioxide containing sodium and iron oxides isused as a polycondensation catalyst. However, these polycondensationcatalysts cannot achieve the object of reducing the content of antimonyin polyester.

[0009] As a method of solving the problem of the antimony catalyst inuses requiring transparency of PET bottles etc., for example JP-A6-279579 discloses a method of improving transparency by prescribing theproportion of antimony and phosphorus compounds used. However, it cannotbe said that hollow molded articles made of polyester obtained by thismethod are sufficiently transparent.

[0010] Further, JP-A 10-36495 discloses a continuous process forproducing polyester excellent in transparency, which comprises use ofantimony trioxide, phosphoric acid and a sulfonic acid compound.However, polyester obtained by such a method has lower thermalstability, and there is the problem of a high content of acetaldehyde inthe resultant hollow molded article.

[0011] Polycondensation catalysts substituted for antimony typecatalysts such as antimony trioxide have also been examined, andtitanium compounds such as tetraalkoxy titanate or tin compounds havepreviously been proposed, but there is a problem that polyester producedby using these compounds is easily thermally degraded during meltmolding, and the polyester is significantly discolored.

[0012] In an attempt at solving the problem arising when such titaniumcompounds are used as the polycondensation catalyst, for example JP-A55-116722 proposes a method of simultaneously using tetraalkoxy titanatein combination with a cobalt salt and a calcium salt. Further, JP-A8-73581 proposes a method of using tetraalkoxy titanate in combinationwith a cobalt compound as the polycondensation catalyst andsimultaneously using an optical brightener. By these techniques, PETdiscoloration occurring when tetraalkoxy titanate is used as thepolycondensation catalyst can be reduced, but prevention of thermaldecomposition of PET cannot be achieved.

[0013] In another attempt at preventing thermal degradation during meltmolding of polyester polymerized in the presence of a titanium compoundas the catalyst, for example JP-A 10-259296 describes a method of addinga phosphorus compound after polymerization of polyester in the presenceof the titanium compound as the catalyst. However, effective mixing ofthe additive with the polymer after polymerization is technicallydifficult and leads to higher costs, so this prior art method is notpractically used under the present circumstances.

[0014] A method of adding an alkali metal compound to an aluminumcompound to form a polyester polymerization catalyst having a sufficientcatalytic activity is also known. When such a known catalyst is used,polyester excellent in thermal stability can be obtained, but this knowncatalyst using an alkali metal compound in combination should be addedin a larger amount in order to attain a practical catalytic activity,and as a result, insoluble particles attributable to the alkali metalcompound are increased, there arises a problem that when the PET is usedin fibers, the spinnability and physical properties of fibers aregetting worse, and when the PET is used in films, the physicalproperties of the films are getting worse, and hydrolytic resistance arelowered.

[0015] As an non-antimony catalyst, having an excellent catalyticactivity and giving polyester excellent in thermal stability andhydrolytic resistance, a germanium compound has been practically used,but this catalyst has a problem that it is very expensive and easilydistilled away from the reaction system during polymerization, thuschanging the concentration of the catalyst in the reaction system andmaking control of polymerization difficult, so use of the germaniumcomponent as a major catalytic component is problematic.

[0016] For preventing thermal degradation of polyester during meltmolding, there is also a method of removing a catalyst from polyester.JP-A 10-251394 discloses a method of removing a catalyst from polyesterwherein a polyester resin is brought into contact with an extractant assupercritical fluid in the presence of an acidic substance. However, themethod of using such supercritical fluid is technically difficult andleads to higher costs for products, and is thus not preferable.

[0017] For the reasons described above, there is demand for apolymerization catalyst which comprises a metal component other thanantimony and germanium as a major catalytic component, has an excellentcatalytic activity and gives polyester hardly suffering thermaldegradation during melt molding and excellent in thermal stability andhydrolytic resistance.

[0018] This invention provides a polyester polymerization catalyst whichcontains neither an antimony compound nor a germanium compound as amajor catalytic component but contains aluminum as a major metalcomponent, has an excellent catalytic activity, and without deactivatingor removing the catalyst, gives polyester effectively inhibited fromsuffering thermal degradation during melt molding and excellent inthermal stability, thermo oxidative stability and hydrolytic resistance.Further, this invention provides polyester produced with the catalyst,which is excellent in thermal stability, thermo oxidative stability andhydrolytic resistance during melt molding of films, hollow moldedarticles such as bottles, and fibers and which is superior in qualitylevel even if virgin resin is used or scraps generated during moldingare reutilized, as well as a process for producing polyester by usingthe polyester polymerization catalyst. Another object of this inventionis to provide fibers, films, sheets and hollow molded articlescomprising the polyester produced with the novel polyesterpolymerization catalyst which contains neither a germanium compound noran antimony compound as a major catalytic component.

DISCLOSURE OF INVENTION

[0019] The polyester polymerization catalyst of this invention ischaracterized by comprising at least one member selected from aluminumand aluminum compounds thereof as a first metal-containing component inthe coexistence of at least one member selected from phosphoruscompounds represented by formulae 1 and 2:

[0020] By using the phosphorus compounds having these specificstructures, there can be provided a polyester polymerization catalystwhich contains neither an antimony compound nor a germanium compound asa major catalytic component but contains aluminum as a major metalcomponent, has an excellent catalytic activity, and without deactivatingor removing the catalyst, gives polyester effectively inhibited fromsuffering thermal degradation during melt molding and excellent inthermal stability and hydrolytic resistance.

[0021] Irganox 1222 and Irganox 1425 (Ciba Specialty Chemicals Inc.) arecommercially available and usable respectively as the compoundsrepresented by the formulae 1 and 2.

[0022] The phosphorus compounds as the catalyst component in thisinvention were known as antioxidants, but even if these phosphorouscompounds are used in combination with conventional metal-containingpolyester polymerization catalysts, their significant promotion of meltpolymerization is not known. Even if the phosphorus compound in thisinvention is added actually for the melt polymerization of polyester bya typical polyester polymerization catalyst such as an antimonycompound, titanium compound, tin compound or germanium compound, itcannot be recognized that the polymerization is promoted tosubstantially useful levels.

[0023] The amount of the phosphorus compound used in this invention ispreferably 0.0001 to 0.1 mol-%, more preferably 0.005 to 0.05 mol-%relative to the number of moles of the whole constituent units ofpolycarboxylic acid components in the resulting polyester.

[0024] By simultaneously using the phosphorus compound in thisinvention, the resulting catalyst can exhibit a sufficient catalyticeffect even if the amount of aluminum added to the polyesterpolymerization catalyst is small. When the amount of the phosphoruscompound added is less than 0.0001 mol-%, the effect of the compoundadded may not be exhibited, while when the compound is added in anamount of higher than 0.1 mol-%, the catalytic activity of the polyesterpolymerization catalyst may be lowered, and this lowering tendency isvaried depending on e.g. the amount of aluminum used.

[0025] There is a method of preventing discoloration resulting from areduction in thermal stability in case a phosphorus compound is not usedand an aluminum compound is used as a major catalyst component, themethod comprising reducing the amount of the aluminum compound used andfurther adding a cobalt compound, but when the cobalt compound is addedat a certain degree to achieve a sufficient catalytic activity, thethermal stability is lowered. Accordingly, this method hardly meets bothprevention of discoloration and thermal stability.

[0026] By using the phosphorus compound having the above-describedspecific chemical structure according to this invention, there can beobtained a polyester polymerization catalyst which even if the amount ofaluminum as the first metal-containing component is low, has asufficient catalytic effect without causing problems such as a reductionin thermal stability, formation of insoluble particles etc., and thispolyester polymerization catalyst can be used to solve thermal stabilityetc. of polyester films, hollow molded articles such as bottles, fibers,and engineering plastics during melt molding. Addition of phosphoricacid or a phosphate such as trimethyl phosphate in place of thephosphorus compound in this invention is not practical because theredoes not bring about any effect of the compound added. Further, even ifthe phosphorus compound in this invention is used in the amount definedin this invention in combination with a conventional metal-containingpolyester polymerization catalyst such as antimony compound, titaniumcompound, tin compound or germanium compound, there does not bring aboutany effect of promoting the melt polycondensation reaction. Even if thephosphorus compound in this invention is used alone in the range of theamount defined in this invention, no catalytic activity is recognized.

[0027] Preferably, the polyethylene terephthalate (PET) polymerized byusing the polyester polymerization catalyst of this invention satisfiesboth the relationship (1) below for thermal stability (TS) parameter asan indicator of polyester thermal stability, the relationship (2) belowfor hydrolytic stability (HS) parameter as an indicator of hydrolysisstability and the relationship (3) below for thermal oxidation stability(TOS) parameter.

TS<0.3  (1)

[0028] wherein TS is a numerical value calculated in the equationTS=0.245 {[IV]_(f) ^(−1.47)−[IV]_(i) ^(−1.47)}, from the final intrinsicviscosity ([IV]_(f)) which is determined after 1 g melt-polymerized PETresin chips having an initial intrinsic viscosity ([IV]_(i)) of about0.65 dl/g are placed in a glass test tube, vacuum-dried at 130° C. for12 hours, and maintained in a molten state at 300° C. for 2 hours in anon-circulating nitrogen atmosphere. The non-circulating nitrogenatmosphere refers to a stationary nitrogen atmosphere in which a glasstest tube containing e.g. resin chips is connected to a vacuum line andthe replacement of the atmosphere by nitrogen is conducted five or moretimes by introducing nitrogen under reduced pressure, to achieve anitrogen atmosphere at 100 Torr.

HS<0.10  (2)

[0029] wherein HS is a numerical value calculated in the equationHS=0.245 {[IV]_(f2)−^(1.47)−[IV]_(i) ^(−1.47)}, from the intrinsicviscosity ([IV]_(f2)) which is determined after melt-polymerized resinchips of PET having an initial IV ([IV]_(i)) of about 0.65 dl/g arefrozen and milled to give powders of 20 meshes or less which are thenvacuum-dried at 130° C. for 12 hours, and 1 g of the powders, togetherwith 100 ml purified water, are placed in a beaker and then heated understirring for 6 hours in a closed system at 130° C. under pressure.

[0030] The beaker used in measurement of HS is the one from which noacid or alkali is eluted. Specifically, use of a stainless steel beaker,a quartz beaker etc. is preferable.

TOS<0.10  (3)

[0031] wherein TOS is determined using the equation TOS=0.245 {[IV]_(f3)^(−1.47)−[IV]_(i) ^(−1.47)}, from the intrinsic viscosity ([IV]_(f3)) ofPET which is determined after melt-polymerized resin chips of PET havingan intrinsic viscosity ([IV]_(i)) of about 0.65 dl/g are frozen andmilled to give powders of 20 meshes or less which are then vacuum-driedat 130° C. for 12 hours, and 0.3 g of the powders are placed in a glasstest tube and vacuum-dried at 70° C. for 12 hours and then heated at230° C. for 15 minutes in dry air over silica gel. The method of heatingin dry air over silica gel can be, for example, a method wherein a glasstest tube is heated in air dried by connecting a dry tube containingsilica gel to an upper part of the test tube.

[0032] The PET resin chips used in measurement of TS, TOS and HS in thisinvention are prepared by rapid cooling of PET in a molten stateobtained by usual melt-polymerization. The resin chips used in thismeasurement are, for example, those in the form of a cylinder of about 3mm in length and about 2 mm in diameter. By use of the catalyst thusconstituted, there can be obtained polyester giving molded articlesexcellent in melt thermal stability with less occurrence ofdiscoloration and less formation of insoluble particles during heatmelting in production of molded articles such as films, bottles andfibers. Also, there can be obtained polyester giving molded articlesexcellent in hydrolytic stability and thermo oxidative stability.

[0033] TS is more preferably 0.25 or less, still more preferably 0.20 orless. HS is more preferably 0.09 or less, still more preferably 0.085 orless. TOS is more preferably 0.09 or less, still more preferably 0.08 orless.

[0034] The catalyst of the invention is preferably free of alkalimetals, alkaline earth metals or compounds thereof.

[0035] In a preferable embodiment of this invention, at least one memberselected from alkali metals, alkaline earth metals and compounds thereofis allowed to be coexistent in a small amount as a secondmetal-containing component in addition to aluminum or a compoundthereof. The second metal-containing component is allowed to becoexistent in the catalyst system in order to improve not only theeffect of inhibiting formation of diethylene glycol but also thecatalytic activity, thus providing a catalytic component for increasingthe reaction rate to improve productivity effectively.

[0036] The technique of adding an alkali metal compound or an alkalineearth metal compound to an aluminum compound to form a catalyst having asufficient catalytic activity is known. When such known catalyst isused, polyester excellent in thermal stability can be obtained, but theknown catalyst using an alkali metal compound or an alkaline earth metalcompound in combination with an aluminum compound should be added in alarger amount in order to achieve a practical catalytic activity, anduse of the alkali metal compound causes a reduction in hydrolyticstability of the resulting polyester and an increase in the amount ofinsoluble particles attributable to the alkali metal, and use of thealkali metal compound in producing fibers causes a decrease inproductivity and physical properties of the fiber, while use thereof forproducing films causes a deterioration in film physical properties etc.When the alkaline earth metal compound is used in combination, apractical activity cannot be achieved without degrading the thermalstability of the resultant polyester, while discoloration occurssignificantly upon heating, the amount of insoluble particles isincreased, and hydrolytic stability is lowered.

[0037] When an alkali metal, an alkaline earth metal and compoundsthereof are added, the amount M (mol-%) thereof is preferably in therange of 1×10⁻⁶ to 0.1 mol-%, more preferably 5×10⁻⁶ to 0.05 mol-%,still more preferably 1×10⁻⁵ to 0.03 mol-%, further more preferably1×10⁻⁵ to 0.01 mol-%, relative to the number of moles of the wholepolycarboxylic acid units constituting the polyester. The amount of thealkali metal and alkaline earth metal added is so small that the rate ofreaction can be increased without causing problems such as a reductionin thermal stability, formation of insoluble particles, discoloration, areduction in hydrolytic stability, etc. When the amount M of an alkalimetal, an alkaline earth metal and compounds thereof is 0.1 mol-% ormore, a reduction in thermal stability, formation of insolubleparticles, an increase in discoloration and a reduction in hydrolyticstability can be problematic in manufacturing of products. When M isless than 1×10⁻⁶ mol-%, the effect of the metal added is not evident.

BEST MODE FOR CARRYING OUT THE INVENTION

[0038] As aluminum or aluminum compounds constituting thepolycondensation catalyst of this invention, it is possible to use notonly metal aluminum but also known aluminum compounds withoutlimitation.

[0039] Specifically, the aluminum compounds include carboxylates such asaluminum formate, aluminum acetate, aluminum propionate, aluminumoxalate, aluminum acrylate, aluminum laurate, aluminum stearate,aluminum benzoate, aluminum trichloroacetate, aluminum lactate, aluminumcitrate, aluminum tartrate and aluminum salicylate, inorganic acid saltssuch as aluminum chloride, aluminum hydroxide, aluminum hydroxidechloride, aluminum nitrate, aluminum sulfate, aluminum carbonate,aluminum phosphate and aluminum phosphonate, aluminum alkoxides such asaluminum methoxide, aluminum ethoxide, aluminum n-propoxide, aluminumiso-propoxide, aluminum n-butoxide and aluminum t-butoxide, aluminumchelate compounds such as aluminum acetylacetonate, aluminumacetylacetate, aluminum ethylacetoacetate, aluminum ethylacetoacetatedi-iso-propoxide, organoaluminum compounds such as trimethyl aluminumand triethyl aluminum, and partial hydrolyzates thereof, a reactionproduct consisting of aluminum alkoxide or an aluminum chelate compoundand hydroxycarboxylic acid, and composite oxides of aluminum oxide,superfine particles of aluminum oxide, aluminum silicate, aluminum,titanium, zirconium, alkali metal and alkaline earth metal. Among these,the carboxylates, inorganic acid salts and chelate compounds arepreferable, among which aluminum acetate, aluminum lactate, aluminumchloride, aluminum hydroxide, aluminum hydroxide chloride and aluminumacetylacetonate are particularly preferable.

[0040] Among these aluminum compounds, those having higher aluminumcontents, such as aluminum acetate, aluminum chloride, aluminumhydroxide and aluminum hydroxide chloride, are preferable, and from theviewpoint of solubility, aluminum acetate, aluminum chloride andaluminum hydroxide chloride are preferable. Further, use of aluminumacetate is particularly preferable from the viewpoint of no corrosion ofunits.

[0041] The term “aluminum hydroxide chloride” is a generic name of thosecompounds also called polyaluminum chloride and basic aluminum chloride,and those for use in tap water can be used. These are represented forexample by the general structural formula [Al₂(OH)_(n)Cl_(6-n)]_(m)(1≦n≦5). Among these, those having low chlorine contents are preferablefrom the viewpoint of no corrosion of units.

[0042] The term “aluminum acetate” is a generic name of those compoundshaving an aluminum acetate salt structure, represented by basic aluminumacetate, aluminum triacetate and aluminum acetate solutions, among whichbasic aluminum acetate is used preferably from the viewpoint ofsolubility and stability of the solution. Among the basic aluminumacetate, aluminum monoacetate, aluminum diacetate and their stabilizedcompounds with boric acid are preferable. When the basic aluminumacetate stabilized with boric acid is used, the basic aluminum acetatestabilized with equimolar or less boric acid is preferably used, andparticularly the basic aluminum acetate stabilized with ½ to ⅓ molarboric acid is preferably used. The stabilizer for basic aluminum acetateincludes not only boric acid but also urea and thiourea etc. Theabove-described basic aluminum acetate made solubilized in a solventsuch as water or glycol, particularly the one made solubilized in waterand/or ethylene glycol is used preferably from the viewpoint ofcatalytic activity and qualities of the resulting polyester.

[0043] Hereinafter, the method of preparing a solution of basic aluminumacetate is specifically described.

[0044] (1) Preparation of an Aqueous Solution of Basic Aluminum Acetate

[0045] Water is added to basic aluminum acetate and stirred at roomtemperature for several hours or more. The stirring time is preferably12 hours or more. Thereafter, stirring is carried out at 60° C. or morefor several hours or more. The temperature in this case is preferably inthe range of 60 to 80° C. The stirring time is preferably 3 hours ormore. The concentration of the aqueous solution is preferably 10 g/l to30 g/l, particularly preferably 15 g/l to 20 g/l.

[0046] (2) Preparation of a Solution of Basic Aluminum Acetate inEthylene Glycol

[0047] Ethylene glycol is added to the above aqueous solution. Ethyleneglycol is added in a volume ratio of preferably 1-5, more preferably2-3, to the aqueous solution. The solution is stirred for several hoursat ordinary temperatures, whereby a uniform mixed solution inwater/ethylene glycol is obtained. Thereafter, the solution is heated todistill water away, to give an ethylene glycol solution. The temperatureis preferably 80 to 120° C. The temperature is more preferably 90 to110° C. at which the solution is stirred preferably for several hours todistill water away.

[0048] As the aluminum lactate, the one made solubilized in a solventsuch as water or glycol, particularly the one made solubilized in waterand/or ethylene glycol is used preferably from the viewpoint ofcatalytic activity and qualities of the resulting polyester.

[0049] Hereinafter, the method of preparing a solution of aluminumlactate in ethylene glycol is specifically described.

[0050] An aqueous solution of aluminum lactate is prepared. Thispreparation may be carried at room temperature or under heating,preferably at room temperature. The concentration of the aqueoussolution is 20 g/l to 100 g/l, more preferably 50 to 80 g/l. Ethyleneglycol is added to the aqueous solution.

[0051] Ethylene glycol is added in a volume ratio of preferably 1-5,more preferably 2-3, to the aqueous solution. The solution is stirred atordinary temperatures to give a uniform mixed solution in water/ethyleneglycol, and then the solution is heated to distill water away, to givean ethylene glycol solution. The temperature is preferably 80 to 120° C.The temperature is more preferably 90 to 110° C. at which the solutionis stirred preferably for several hours to distill water away.

[0052] The amount of aluminum or the aluminum compound used in thisinvention is preferably 0.001 to 0.05 mol-%, more preferably 0.005 to0.02 mol-%, relative to the number of moles of the whole constituentunits of carboxylic acid components such as dicarboxylic acids andpolyvalent carboxylic acids in the resultant polyester. When the amountthereof is less than 0.001 mol-%, the catalytic activity may not besufficiently exhibited, while when the amount is higher than 0.05 mol-%,a reduction in thermal stability and thermal oxidation stability andformation of insoluble particles and discoloration attributable toaluminum may be problematic. Thus, a distinctive feature of thepolycondensation catalyst of the invention is that the catalyst exhibitsa significant catalytic activity even in a small amount of the aluminumcomponent added. As a result, the resulting polyester is excellent inthermal stability and thermal oxidation stability with less insolubleparticles and discoloration attributable to aluminum.

[0053] The alkali metal or alkaline earth metal constituting the secondmetal-containing component which is used preferably in combination withaluminum or the compound thereof in this invention is preferably atleast one member selected from Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr and Ba,among which at least one member selected from Li, Na, Mg and compoundsthereof is used more preferably. The alkali metal or alkaline earthmetal compounds include salts of these metals, for example saturatedaliphatic carboxylates such as formate, acetate, propionate, butyrateand oxalate, unsaturated aliphatic carboxylates such as acrylate andmethacrylate, aromatic carboxylates such as benzoate, halogen-containingcarboxylates such as trichloroacetate, hydroxy carboxylates such aslactate, citrate and salicylate, inorganic acid salts such as carbonate,sulfate, nitrate, phosphate, phosphonate, hydrogen carbonate, hydrogenphosphate, hydrogen sulfide, sulfite, thiosulfate, hydrochloride,hydrobromate, chlorate and bromate, organic sulfonates such as 1-propanesulfonate, 1-pentane sulfonate and naphthalene sulfonate, organicsulfates such as lauryl sulfate, alkoxides such as methoxy, ethoxy,n-propoxy, iso-propoxy, n-butoxy and tert-butoxy, chelate compounds suchas acetylacetonate, hydrides, oxides and hydroxides.

[0054] When highly alkaline compounds such as hydroxides among thesealkali metals, alkaline earth metals or compounds thereof are used, theytend to be hardly dissolved in organic solvents, for example diols suchas ethylene glycol or alcohols, so they should be added as an aqueoussolution to the polymerization system, which may be problematic in thepolymerization process. Further, when highly alkaline compounds such ashydroxides are used, the polyester easily undergoes side reactions suchas hydrolysis during polymerization, while the polymerized polyester iseasily discolored, and hydrolytic stability also tends to be lowered.Accordingly, preferable examples of the alkali metals or compoundsthereof or alkaline earth metals or compounds thereof in this inventionare alkali metal salts or alkaline earth metal salts selected fromsaturated aliphatic carboxylate, unsaturated aliphatic carboxylate,aromatic carboxylate, halogen-containing carboxylate, hydroxycarboxylate, sulfate, nitrate, phosphate, phosphonate, hydrogenphosphate, hydrogen sulfide, sulfite, thiosulfate, hydrochloride,hydrobromate, chlorate and bromate, as well as other inorganic acidsalts, organic sulfonates, organic sulfates, chelate compounds andoxides. Among these, alkaline metal or alkaline earth metal saturatedaliphatic carboxylates particularly acetates are preferably used fromthe viewpoint of easy handling and easy availability.

[0055] In a preferable embodiment, a cobalt compound is further added inan amount of less than 10 ppm in terms of cobalt atom to the polyesterof this invention. The amount is more preferably 5 ppm or less, stillmore preferably 3 ppm or less.

[0056] It is known that the cobalt compound itself has a polymerizationactivity at a certain degree, but when it is added in such an amount asto exhibit a sufficient catalytic effect, the thermal stability of theresultant polyester is lowered as described above. The polyesterobtained according to this invention is excellent in thermal stability,and by adding the cobalt compound in such a small amount that thecatalytic effect thereof is not evident, the discoloration of theresultant polyester can be effectively diminished. The object of thecobalt compound in this invention is to diminish discoloration, and thecobalt compound may be added at any stage of polymerization or afterpolymerization reaction, or at any stage between polymerization reactionand molding.

[0057] The cobalt compound is not particularly limited, and specificexamples thereof include cobalt acetate, cobalt nitrate, cobaltchloride, cobalt acetyl acetonate and cobalt naphthenate or hydratesthereof. Among these, cobalt acetate.4H₂O is particularly preferable.

[0058] In another preferable embodiment, color tone improvers other thanthe cobalt compound are used to improve the color tone of the polyesterof the invention. The color tone improvers refer to those materialswhich upon addition, change the color tone. The color tone improvers inthis invention are not particularly limited, but inorganic and organicpigments, dyes and optical brighteners are preferable.

[0059] When pigments or dyes are used, there arises a problem that whentheir amount is increased, the brightness of the polymer is lowered.Accordingly, there arises a problem that the polymer becomesunacceptable in many uses. Accordingly, the total amount of the pigmentsand dyes used is preferably 20 ppm or less, more preferably 10 ppm orless, still more preferably 5 ppm or less, relative to the resultingpolyester. In this range, discoloration can be effectively preventedwithout lowering the brightness of the polymer.

[0060] Further, use of the optical brightener singly or in combinationwith another color tone improver is preferable because the color tone isimproved so that for example the amount of the pigment or dye used canbe reduced. As the optical brightener, those conventionally used may beused alone or as a mixture thereof. The amount thereof is preferably 50ppm or less, more preferably 5 to 25 ppm, relative to the resultingpolyester.

[0061] The inorganic pigment in the invention is not particularlylimited insofar as the color tone can be changed, and examples thereofinclude titanium dioxide, carbon black, black iron oxide, nickeltitanium yellow, yellow oxide, cadmium yellow, chrome yellow, chrometitanium yellow, zinc ferrite pigment, red oxide, cadmium red,molybdenum red, chrome oxide, spinel green, chrome orange, cadmiumorange, ultramarine, Prussian blue, cobalt blue etc. Among these, chromeoxide, ultramarine, Prussian blue and cobalt blue are preferable, andultramarine and cobalt blue are more preferable. These inorganicpigments may be used alone or as a mixture of two or more thereof asnecessary.

[0062] The organic pigments and dyes in this invention are not limitedinsofar as their color tone can be changed, and examples thereof arethose indicated by color index, such as Pigment Red 5, 22, 23, 31, 38,48:1, 48:2, 48:3, 48:4, 52, 53:1, 57:1, 122, 123, 144, 146, 151, 166,170, 177, 178, 179, 187, 202, 207, 209, 213, 214, 220, 221, 247, 254,255, 263, 272, Pigment Orange 13, 16, 31, 36, 43, 61, 64, 71, PigmentBrown 23, Pigment Yellow 1, 3, 12, 13, 14, 17, 55, 73, 74, 81, 83, 93,94, 95, 97, 109, 110, 128, 130, 133, 136, 138, 147, 150, 151, 154, 180,181, 183, 190, 191, 191:1, 199, Pigment Green 7, 36, Pigment Blue 15,15:1, 15:2, 15:3, 15.4, 15:6, 29, 60, 64, 68, Pigment Violet 19, 23, 37,44, Solvent Red 52, 117, 135, 169, 176, Disperse Red 5, Solvent Orange63, 67, 68, 72, 78, Solvent Yellow 98, 103, 105, 113, 116, DiverseYellow 54, 64, 160, Solvent Green 3, 20, 26, Solvent Blue 35, 45, 78,90, 94, 95, 104, 122, 132, Solvent Violet 31, etc. In addition, otherdyes/pigments based on anthraquinone, phthalocyanine, quinacridone,isoindoline, dioxazine, quinophthalone, perylene, perynone,benzimidazolone, diarylide, vat, indigo, quinophthalone,diketopyrrolopyrrole and anthrapyrrolidone can be mentioned.

[0063] Among these, Pigment Red 187, 263, Pigment Blue 15:1, 15:3, 29,60, Pigment Violet 19, Solvent Red 135, Solvent Blue 45, 90, 104, 122and anthraquinone- and phthalocyanine-based dyes/pigments areparticularly preferable.

[0064] The pigment and/or dye selected are preferably those satisfyingthe following conditions: First, the pigment and dye should be notextractable from the polymer in order to bring about the maximum safety.They should be stable to sunrays and to temperature and humid conditionsin a wide range. Sublimation or color tone change should not occur atvery high temperatures in production of the polyester. Further, thepigment and dye are preferably those not adversely affecting thephysical properties of the polyester polymer.

[0065] The pigment and/or dye is not particularly limited insofar asthey satisfy these conditions and improve the color tone of thepolyester, and for example, color tone improvers using blue1,4-bis(2,6-dialkylanilino) anthraquinone as a main component incombination with red anthraquinone and anthrapyridone(3H-dibenzo[fi,j]isoquinoline-2,7-dione) depending on color tone, etc.are exemplified in Japanese Patent Application National Publication(Laid-Open) No. 2000-511211, and these can be used. These dyes havesuitable color characteristics, are stable to heat, light, humidity andvarious environmental factors, can be incorporated into a polyesterpolymer structure during polymerization, and solve many problems ofknown organic dyes. Further, they are stable to UV rays, hightemperatures, glycolysis and hydrolysis. The amounts of the blue and redcomponents can be changed as necessary to effectively work for polyesterhaving different degrees of coloration.

[0066] As the optical brightener in this invention, those used generallymay be used alone or in combination thereof. For example,benzoxazoline-based optical brighteners, preferably UVITEX OB, UVITEXOB-P and UVITEX OB-ONE manufactured by Ciba Specialty Chemicals,HOSTALUX KS manufactured by Clariant, and those described in JP-A10-1563 can be exemplified and preferably used.

[0067] The color tone improvers of different types can be combined in anarbitrary ratio in order to achieve achromatic color tone. Further, thecolor tone improver may be added at any polymerization stages or afterpolymerization reaction or any stages between polymerization reactionand molding. When added during polymerization, the color tone improveris added preferably in a powdery form or as a mixture thereof dissolvedin one polyester monomer. When added after polymerization reaction, thecolor tone improver is added preferably as powder or a master batch.

[0068] When there is a problem in dispersibility of pigments etc., itmay be preferable to use a dispersant as necessary. The dispersant isnot particularly limited insofar as it facilitates dispersion of thepigment, and examples thereof include N,N′-alkylene-bis-fatty acidamides such as N,N′-ethylene-bis-myristic acid amide,N,N′-ethylene-bis-stearic acid amide, N,N′-ethylene-bis-oleic acidamide, N,N′-methylene-bis-myristic acid amide,N,N′-methylene-bis-stearic acid amide, N,N′-methylene-bis-oleic acidamide, etc. Among these, N,N′-methylene-bis-stearic acid amide ispreferable. The amount of the dispersant added is varied depending onperformance, but the dispersant may be added in an amount of 10 to 200wt-%, preferably 40 to 150 wt-%, relative to the pigment.

[0069] Production of polyester according to the present invention can becarried out in the same manner as in the conventional process exceptthat the polyester polymerization catalyst of this invention is used asthe catalyst. For example, PET is produced by a direct esterificationmethod wherein terephthalic acid and ethylene glycol and if necessaryother copolymerizable components are directly reacted to form an esterwhile water is distilled away, followed by polycondensation underreduced pressure or by a transesterification method wherein dimethylterephthalate and ethylene glycol and if necessary other copolymerizablecomponents are reacted for transesterification while methyl alcohol isdistilled away, followed by polycondensation under reduced pressure. Ifnecessary, solid state polymerization may also be conducted in order toincrease the intrinsic viscosity. For promotion of crystallizationbefore solid state polymerization, melt-polymerized polyester is allowedto absorb water vapor and then crystallized by heating, or polyesterchips are sprayed directly with water vapor and then crystallized byheating.

[0070] The melt polycondensation reaction may be conducted in a reactionunit in a batch system or a reaction unit in a continuous system. Ineither system, the esterification reaction or transesterificationreaction may be conducted at one stage or divided stages. The meltpolycondensation reaction may also be conducted at one stage or dividedstages. The solid state polymerization reaction, similar to the meltpolycondensation reaction, can be conducted in a reaction unit in abatch system or a reaction unit in a continuous system. The meltpolycondensation and solid state polymerization can be conductedcontinuously or successively. The process for producing polyethyleneterephthalate in a continuous system is described in detail below byreference to a preferable embodiment.

[0071] First, production of a low polymer by esterification reaction isdescribed. Slurry containing 1.02 to 1.5 moles, preferably 1.03 to 1.4moles of ethylene glycol per mole of terephthalic acid or an esterderivative thereof is prepared and fed continuously to theesterification reaction process.

[0072] The esterification reaction is conducted with ethylene glycolrefluxed in a multistage unit consisting of 1 to 3 esterificationreactors connected in series, during which water or alcohol formed bythe reaction is discharged from the reaction system through adistillation column. The temperature in the esterification reaction atthe first stage is 240 to 270° C., preferably 245 to 265° C., thepressure is 0.2 to 3 kg/cm²G (0.02 to 0.3 Mpa·G, that is, under apressure of 0.02 to 0.3 MPa=atmospheric pressure +0.02 to 0.3 MPa),preferably 0.5 to 2 kg/cm²G. The temperature in the esterificationreaction at the final stage is usually 250 to 290° C., preferably 255 to275° C., and the pressure is usually 0 to 1.5 kg/cm²G, preferably 0 to1.3 kg/cm²G. When the reaction is conducted at three or more stages, theesterification reaction conditions for intermediate stages areintermediate conditions between the conditions at the first stage andfinal stage. The degree of the esterification reaction is preferablyevenly increased at the respective stages. Desirably, the degree ofesterification finally attains 90% or more, preferably 93% or more. Bythese esterification reactions, low-condensed products of molecularweights of about 500 to 5000 can be obtained.

[0073] When terephthalic acid is used as the starting material, theesterification reaction can be conducted in the absence of a catalystbecause terephthalic acid has a catalytic activity as the acid, but thereaction may also be conducted in the coexistence of a polymerizationcatalyst.

[0074] Because the ratio of dioxyethylene terephthalate units in a majorchain of polyethylene terephthalate can be kept at a low level (5 mol-%or less relative to the whole total diol components), the reaction iscarried out preferably in the presence of a small amount of tertiaryamines such as triethylamine, tri-n-butylamine and benzyl dimethylamine,quaternary ammonium hydroxides such as tetraethyl ammonium hydroxide,tetra-n-butyl ammonium hydroxide and trimethyl benzyl ammoniumhydroxide, and basic compounds such as lithium carbonate, sodiumcarbonate, potassium carbonate and sodium acetate.

[0075] When oligomer is produced by transesterification reaction, asolution containing ethylene glycol in an amount of 1.1 to 1.6 moles,preferably 1.2 to 1.5 moles per mole of dimethyl terephthalate isprepared and fed continuously to the transesterification reactionprocess.

[0076] The transesterification reaction is conducted with ethyleneglycol refluxed in a multistage unit consisting of 1 or 2 esterificationreactors connected in series, during which methanol formed by thereaction is discharged from the reaction system through a distillationcolumn. The temperature of the transesterification reaction at the firststage is 180 to 250° C., preferably 200 to 240° C. The temperature ofthe transesterification reaction at the final stage is usually 230 to270° C., preferably 240 to 265° C., and Zn, Cd, Mg, Mn, Co, Ca and Bafatty acid salts and carboxylic acid salts, and Pb, Zn, Sb and Ge oxidesare used as the transesterification catalyst. Low-condensed productswith molecular weights of about 200 to 500 are obtained by thesetransesterification reactions.

[0077] Then, the resultant low-condensed products are fed to amultistage liquid phase polycondensation process. The polycondensationreaction conditions are selected such that the temperature for thepolycondensation reaction at the first reaction stage is 250 to 290° C.,preferably 260 to 280° C., the pressure is 500 to 20 Torr, preferably200 to 30 Torr, and the temperature for the polycondensation reaction atthe final stage is 265 to 300° C., preferably 275 to 295° C., and thepressure is 10 to 0.1 Torr, preferably 5 to 0.5 Torr. When the reactionis carried out at three or more stages, the reaction conditions for thepolycondensation reaction at intermediate stages are intermediateconditions between the reaction conditions at the first stage and finalstage. Preferably, the increase in the intrinsic viscosity is achievedevenly at the respective polycondensation reaction stages.

[0078] When a low content of acetaldehyde or a low content of cyclictrimers in e.g. low-flavor drinks or heat-resistant hollow moldedproducts for mineral water is required, the melt-polycondensed polyesterthus obtained is subjected to solid state polymerization. The polyesteris subjected to solid state polymerization in a method known in the art.First, the polyester to be subjected to solid state polymerization ispreliminarily crystallized by heating at a temperature of 100 to 210° C.for 1 to 5 hours in an inert gas or under reduced pressure or in watervapor or in an atmosphere of inert gas containing water vapor. Then,solid state polymerization is carried out at a temperature of 190 to230° C. for 1 to 30 hours in an inert gas atmosphere or under reducedpressure.

[0079] The method of reducing the content of cyclic trimers is notlimited to solid state polymerization. For example, a method ofdeactivating the catalyst with hot water etc. or a method of heattreatment in an inert gas known in the art may be used. The heattreatment method known in the art includes those methods described ine.g. JP-A 2-298512, JP-A 8-120062 etc.

[0080] The temperature for the heat treatment is a temperature of from180° C. to the melting point of the polyester. The temperature forordinary polyethylene terephthalate is preferably 190 to 260° C.,particularly preferably 200 to 250° C.

[0081] The time for the heat treatment is preferably 2 hours or more.Usually, the treatment time is preferably 2 to 60 hours, more preferably2 to 40 hours.

[0082] The content of water vapor in the atmosphere for the heattreatment is preferably 1000 ppm or less, more preferably 500 ppm orless, still more preferably 400 ppm or less. The oxygen concentration ispreferably 1000 ppm or less, more preferably 500 ppm or less, still morepreferably 100 ppm or less, most preferably 50 ppm or less.

[0083] The inert gas used is preferably a gas inert to the polyesterobtained in this invention, and examples thereof include a nitrogen gas,carbon dioxide gas, helium gas etc. In particular, a nitrogen gas isinexpensive and thus preferable.

[0084] As a condition for the heat treatment, either a non-circulatinginert gas atmosphere or an atmosphere with a circulating inert gasstream can be selected as an inert gas atmosphere.

[0085] When heat treatment is carried out in a substantiallynon-circulating inert gas, the polyester is heat-treated in aheat-treatment chamber under slightly pressurized conditions with theinert gas described above. When heat treatment is carried out in asubstantially circulating inert gas stream, heat treatment is carriedout usually at normal pressure, but may be carried out under pressurizedconditions of not higher than 5 kg/cm². In this case, the glycolcomponent used in production of the polyester of this invention ispreferably contained in the atmosphere. On the other hand, the flow rateof the inert gas is related closely to the intrinsic viscosity of thepolyester, so the flow rate should be determined suitably depending onthe concentration of glycol contained, the intrinsic viscosity ofdesired polyester and heat treatment temperature.

[0086] The unit for heat treatment is desirably an unit wherein thepolyester can be uniformly contacted with the inert gas. Such heattreatment units include, for example, a stationary dryer, a rotarydryer, a fluidized bed dryer, a dryer having a stirring blade, and aglass test tube.

[0087] The catalyst of this invention has a catalytic activity not onlyin polycondensation reaction but also in esterification reaction andtransesterification reaction. For example, polymerization bytransesterification reaction between an alkyl dicarboxylate such asdimethyl terephthalate and a glycol such as ethylene glycol is conductedusually in the presence of a transesterification catalyst such as atitanium compound or a zinc compound, but the catalyst of this inventioncan also be used in place of such catalyst or in the coexistence of suchcatalyst. Further, the catalyst of this invention also has a catalyticactivity not only in melt polymerization but also in solid statepolymerization and solution polymerization, and in any methods,polyester can be produced.

[0088] The polycondensation catalyst of this invention can be added tothe reaction system at an arbitrary stage of the polymerizationreaction. For example, the catalyst can be added to the reaction systembefore or during esterification reaction or transesterification reactionor just before or during polycondensation reaction. In particular,aluminum or a compound thereof is added preferably just beforepolycondensation reaction.

[0089] The method of adding the polycondensation catalyst of thisinvention is not particularly limited, and the catalyst may be added ina powdery or neat state or in the form of a solution or slurry in asolvent such as ethylene glycol. Alternatively, an aluminum metal or acompound thereof and another component preferably the phosphoruscompound in this invention may be added as a mixture, or thesecomponents may be added separately. Alternatively, an aluminum metal ora compound thereof and another component preferably the phosphoruscompound may be added simultaneously to the polymerization system, orthese components may be added separately at different stages. Further,the catalyst may be added in one portion or in divided portions.

[0090] When a mixture of the aluminum compound and the phosphoruscompound constituting the polycondensation catalyst of the invention isused as the catalyst, the phosphorus compound in this invention may beadded to a previously prepared solution of the aluminum compound, or thealuminum compound may be added to a previously prepared solution of thephosphorus compound, in order to prepare the catalyst. Alternatively,solutions of the two components may be mixed or the two may be dissolvedsimultaneously in a solvent. As the solvent, glycols such as ethyleneglycol, water or other solvents can be used, but water and/or ethyleneglycol is preferably used. The solution may be prepared at ordinarytemperatures or under heating. The catalyst may be used not only as asolution but also as slurry containing the two components or a mixturecontaining the two in a powdery form.

[0091] To improve productivity by shortening the polymerization time, itis effective and preferable that the polycondensation catalyst of thisinvention is used in the coexistence of another polycondensationcatalyst such as an antimony compound, a germanium compound or atitanium compound in such an amount as not to cause the above problemsin the properties, processability and color tone of polyester.

[0092] The antimony compound is added preferably in an amount of 50 ppmor less in terms of antimony atom relative to the polyester obtained bypolymerization. The antimony compound is added more preferably in anamount of 30 ppm or less. An amount of antimony greater than 50 ppm isnot preferable because an antimony metal is precipitated to cause graydiscoloration or to form insoluble particles in the polyester.

[0093] The germanium compound is added preferably in an amount of 20 ppmor less in terms of germanium atom relative to the polyester obtained bypolymerization. The germanium compound is added more preferably in anamount of 10 ppm or less. An amount of germanium greater than 20 ppm iseconomically disadvantageous and thus not preferable.

[0094] The titanium compound is added preferably in the range of 5 ppmor less in terms of titanium atom relative to the polymer obtained bypolymerization. The titanium compound is added more preferably in anamount of preferably 3 ppm or less, still more preferably 1 ppm or less.It is not desirable that titanium is added in an amount of higher than 5ppm, because the discoloration of the resultant resin is significant andthe thermal stability is significantly degraded.

[0095] The antimony compound usable in this invention is notparticularly limited, and preferable compounds include antimonytrioxide, antimony pentaoxide, antimony acetate, antimony glucoxideetc., among which antimony trioxide is preferably used. The germaniumcompound includes, but is not limited, to germanium dioxide, germaniumtetrachloride etc., among which germanium dioxide is preferable.Germanium dioxide used may be crystalline or amorphous.

[0096] The titanium compound usable in this invention includes, but isnot limited, tetra-n-propyl titanate, tetra-isopropyl titanate,tetra-n-butyl titanate, tetra-isobutyl titanate, tetra-tert-butyltitanate, tetracyclohexyl titanate, tetraphenyl titanate, tetrabenzyltitanate, lithium oxalate titanate, potassium oxalate titanate, ammoniumoxalate titanate, titanium oxide, composite oxides of titanium andsilicon or zirconium and an alkali metal or alkaline earth metal, anortho-ester or condensed ortho-ester of titanium, a reaction productconsisting of an ortho-ester or condensed ortho-ester of titanium and ahydroxycarboxylic acid, a reaction product consisting of an ortho-esteror condensed ortho-ester of titanium, a hydroxycarboxylic acid and aphosphorus compound, a polyvalent alcohol having an ortho-ester orcondensed ortho-ester of titanium and at least 2 hydroxyl groups, and areaction product consisting of 2-hydroxycarboxylic acid and a base,among which a composite oxide of titanium and silicon, a composite oxideof titanium and magnesium, and a reaction product consisting of anortho-ester or condensed ortho-ester of titanium, a hydroxycarboxylicacid and a phosphorus compound are preferable.

[0097] The tin compound includes dibutyltin oxide, methylphenyltinoxide, tetraethyl tin, hexaethylditin oxide, triethyltin hydroxide,monobutyl hydroxytin oxide, triisobutyltin acetate, diphenyltindilaurate, monobutyltin trichloride, dibutyltin sulfide, dibutylhydroxytin oxide, methylstannic acid, ethyl stannate etc., among whichmonobutyl hydroxytin oxide is preferably used.

[0098] The polyester in this invention refers to polyester comprisingone or more members selected from polyvalent carboxylic acids includingdicarboxylic acids and ester-forming derivatives thereof and one or moremembers selected from polyvalent alcohols including glycols, topolyester comprising one or more members selected form hydroxycarboxylicacids and ester-forming derivatives thereof, or to polyester comprisingcyclic esters.

[0099] The dicarboxylic acids include saturated aliphatic dicarboxylicacids such as oxalic acid, malonic acid, succinic acid, glutaric acid,adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid,decane dicarboxylic acid, dodecane dicarboxylic acid, tetradecanedicarboxylic acid, hexadecane dicarboxylic acid, 3-cyclobutanedicarboxylic acid, 1,3-cyclopentane dicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexane dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-norbornane dicarboxylic acid and dimer acid orester-forming derivatives thereof, unsaturated aliphatic dicarboxylicacids such as fumaric acid, maleic acid and itaconic acid orester-forming derivatives thereof, and aromatic dicarboxylic acids suchas orthophthalic acid, isophthalic acid, terephthalic acid, diphenineacid, 1,3-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylicacid, 1,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylicacid, 2,7-naphthalene dicarboxylic acid, 4,4′-biphenyl dicarboxylicacid, 4,4′-biphenyl sulfone dicarboxylic acid, 4,4′-biphenyl etherdicarboxylic acid, 1,2′-bis(phenoxy) ethane-p,p′-dicarboxylic acid,pamoinic acid and anthracene dicarboxylic acid or ester-formingderivatives thereof.

[0100] Among these dicarboxylic acids, terephthalic acid, isophthalicacid and naphthalene dicarboxylic acid are particularly preferably usedfor the physical properties of the resultant polyester, and if necessaryother dicarboxylic acids are used as constituent components.

[0101] The polyvalent carboxylic acids other than these dicarboxylicacids include ethane tricarboxylic acid, propane tricarboxylic acid,butane tetracarboxylic acid, pyromellitic acid, trimellitic acid,trimesic acid, 3,4,3′,4′-biphenyl tetracarboxylic acid and ester-formingderivatives thereof.

[0102] The glycols include aliphatic glycols such as ethylene glycol,1,2-propylene glycol, 1,3-propylene glycol, diethylene glycol,triethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol,2,3-butylene glycol, 1,4-butylene glycol, 1,5-pentane diol, neopentylglycol, 1,6-hexane diol, 1,2-cylohexane diol, 1,3-cylohexane diol,1,4-cyclohexane diol, 1,2-cyclohexane dimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexane dimethanol, 1,4-cyclohexane diethanol,1,10-decamethylene glycol, 1,12-dodecane diol, polyethylene glycol,polytrimethylene glycol and polytetramethylene glycol, and aromaticglycols such as hydroquinone, 4,4-dihydroxybisphenol,1,4-bis(β-hydroxyethoxy) benzene, 1,4-bis(β-hydroxyphenyl) sulfone,bis(p-hydroxyphenyl) ether, bis(p-hydroxyphenyl) sulfone,bis(p-hydroxyphenyl) methane, 1,2-bis(p-hydroxyphenyl) ethane, bisphenolA, bisphenol C, 2,5-naphthalene diol, and glycols having ethylene oxideadded to these glycols.

[0103] Among these glycols, ethylene glycol, 1,3-propylene glycol,1,4-butylene glycol and 1,4-cyclohexane dimethanol are particularlypreferably used as major components.

[0104] The polyvalent alcohols other than these glycols includetrimethylol methane, trimethylol ethane, trimethylol propane,pentaerythritol, glycerol, and hexane triol.

[0105] The hydroxycarboxylic acids include lactic acid, citric acid,malic acid, tartaric acid, hydroxyacetic acid, 3-hydroxybutyric acid,p-hydroxybenzoic acid, p-(2-hydroxyethoxy) benzoic acid,4-hydroxycyclohexane carboxylic acid or ester-forming derivativesthereof.

[0106] The cyclic esters include ε-caprolactone, β-propiolactone,β-methyl-β-propiolactone, δ-valerolactone, glycolide and lactide.

[0107] The ester-forming derivatives of polyvalent carboxylic acids orhydroxycarboxylic acids include alkyl esters, acid chlorides and acidanhydrides thereof.

[0108] The polyester used in this invention is polyester whose majoracid component is terephthalic acid or an ester-forming derivativethereof or naphthalene dicarboxylic acid or an ester-forming derivativethereof, preferably polyester whose major glycol component is analkylene glycol.

[0109] The polyester whose major acid component is terephthalic acid oran ester-forming derivative thereof is polyester wherein the totalcontent of terephthalic acid or an ester-forming derivative ispreferably 70 mol-% or more, more preferably 80 mol-% or more and mostpreferably 90 mol-% or more, relative to the whole acid components. Thepolyester whose major acid component is naphthalene dicarboxylic acid oran ester-forming derivative thereof is polyester wherein the totalcontent of naphthalene dicarboxylic acid or an ester-forming derivativeis preferably 70 mol-% or more, more preferably 80 mol-% or more andmost preferably 90 mol-% or more, relative to the whole acid components.

[0110] The polyester whose major glycol component is an alkylene glycolis polyester wherein the total content of the alkylene glycol ispreferably 70 mol-% or more, more preferably 80 mol-% or more and mostpreferably 90 mol-% or more, relative to the whole glycol components. Asused herein, the alkylene glycol may contain a substituent group or analicyclic structure in the molecule chain thereof.

[0111] The naphthalene dicarboxylic acid or ester-forming derivativesthereof used in this invention are preferably those exemplified above asthe dicarboxylic acids, that is, 1,3-naphthalene dicarboxylic acid,1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid,2,6-naphthalene dicarboxylic acid or 2,7-naphthalene dicarboxylic acid,or ester-forming derivatives thereof.

[0112] As the alkylene glycol used in the invention, it is preferable touse those exemplified above as glycols, that is, ethylene glycol,1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol,1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol,1,5-pentane diol, neopentyl glycol, 1,6-hexane diol, 1,2-cyclohexanediol, 1,3-cyclohexane diol, 1,4-cyclohexane diol, 1,2-cyclohexanedimethanol, 1,3-cyclohexane dimethanol, 1,4-cyclohexane dimethanol,1,4-cyclohexane diethanol, 1,10-decamethylene glycol, 1,12-dodecane dioletc. Two or more of these compounds may be simultaneously used.

[0113] The polyester of this invention include polyethyleneterephthalate, polybutylene terephthalate, polypropylene terephthalate,poly(1,4-cyclohexane dimethylene terephthalate), polyethylenenaphthalate, polybutylene naphthalate, polypropylene naphthalate andcopolymers thereof, among which polyethylene terephthalate andcopolymers thereof are particularly preferable.

[0114] The polyester of this invention can also contain a knownphosphorus compound as a copolymerizable component. The phosphoruscompound is preferably a bifunctional phosphorus type compound such as,for example, (2-carboxyethyl) methylphosphinic acid, (2-carboxyethyl)phenylphosphinic acid, and 9,10-dihydro-10-oxa-(2,3-carboxypropyl)-10-phosphaphenanthrene-10-oxide. Thesephosphorus type compounds can be contained as copolymerizable componentsto improve e.g. the flame retardancy of the resultant polyester.

[0115] In a preferable embodiment, polycarboxylic acids having an alkalimetal sulfonate base are used as copolymerizable components of thepolyester in this invention in order to improve dyeing properties whenthe polyester is used as fibers.

[0116] The metal sulfonate group-containing compound used as acopolymerizable monomer includes, but is not limited to, 5-sodiumsulfoisophthalic acid, 2-sodium sulfoterephthalic acid, 5-lithiumsulfoisophthalic acid, 2-lithium sulfoterephthalic acid, 5-potassiumsulfoisophthalic acid and 2-potassium sulfoterephthalic acid or loweralkyl ester derivatives thereof. In this invention, 5-sodiumsulfoisophthalic acid or ester-forming derivatives thereof arepreferably used.

[0117] The amount of the metal sulfonate-group containing compoundcopolymerized is preferably 0.3 to 10.0 mol-%, more preferably 0.80 to5.0 mol-%, relative to the acid components constituting the polyester.When the amount of the compound copolymerized is too low, the resultantpolyester is inferior in dyeability with cationic dyes, and when theamount of the compound copolymerized is too high, fibers produced fromthe resultant polyester may be inferior in fiber productivity and mayfail to achieve sufficient strength due to the phenomenon of thickening.Further, when the metal sulfonate-containing compound is copolymerizedin an amount of 2.0 mol-% or more, the resultant modified polyesterfibers can also be endowed with dyeability at normal pressure. Byselecting suitable easy dyeable monomers, the amount of the metalsulfonate group-containing compound used can be suitably reduced. Theeasy dyeable monomers include, but are not limited to, long-chain glycolcompounds such as polyethylene glycol, polytetraethylene glycol andaliphatic dicarboxylic acids such as adipic acid, sebacic acid andazelaic acid.

[0118] After the polyester is polymerized according to the process ofthis invention, the thermal stability of the polyester can be furtherimproved by removing the catalyst from the polyester or by adding aphosphorus type compound to deactivate the catalyst.

[0119] The polyester of this invention may contain other arbitrarypolymers, antistatic agents, antifoaming agents, dyeing improvers, dyes,pigments, delusterants, optical brighteners, stabilizers, antioxidantsand other additives. As the antioxidant, antioxidants such as aromaticamine type or phenol type can be used, and as the stabilizers,stabilizers of phosphorus type such as phosphoric acid and phosphate orstabilizers of sulfur or amine type can be used.

[0120] These additives can be added at an arbitrary stage during orafter polymerization of polyester or during molding of polyester, andthe suitable stage at which the additives are to be added is varieddepending on the characteristics of the compound and the performancerequirement of molded articles of polyester.

[0121] The polyester polymerized by using the polyester polymerizationcatalyst of this invention can be used to produce fibers in a usualmanner by melt spinning wherein spinning and drawing of the polyestermay be conducted in 1 or 2 steps. Further, any processes for producingstaple fibers by crimping, heat setting and cutting and any knownprocesses producing fibers such as monofilaments can also be used.

[0122] The resultant fibers can be various fibers with an odd-shapedsection, hollow fibers, composite fibers and dope dyed yarns, and formanufacturing of yarn, for example known techniques such as strandmixing and mixed spinning can also be used.

[0123] Further, the polyester fibers can be used as fiber structuressuch as woven fabrics or nonwoven fabrics.

[0124] The polyester fibers can be used as fibers for clothing, interiorand bedding fibers in curtains, carpets, futon cotton and fiberfill,fibers for industrial materials such as high tensile strings for tirecords and ropes, civil engineering and building materials, andautomobile materials such as air bags, and various kinds of fibers forvarious fabrics, knitting, nets, and nonwoven fabrics of staple orfilament fibers.

[0125] The polyester resin of this invention is used preferably ashollow molded articles.

[0126] The hollow molded articles include drink containers for mineralwater, juice, wine or whiskey, baby's bottles, containers for cannedfoods, containers for hair conditioners and cosmetics, containers fordetergents for houses and tableware.

[0127] Among these containers, the hollow molded articles of thisinvention are particularly preferable as pressure-resistant containers,heat-resistant and pressure-resistant containers and alcohol-resistantcontainers utilizing the sanitary conditions, strength and solventresistance of the polyester.

[0128] For production of the hollow molded articles, preliminaryclosed-end molded articles are obtained by a method wherein polyesterchips obtained by melt polymerization or solid state polymerization aredried by e.g. vacuum drying and then molded by an extrusion moldingmachine or an injection molding machine, or by a direct molding methodwherein after melt polymerization, the melt is introduced in a moltenstate into a molding machine and molded. The preliminary molded articlesare subjected to blow molding such as drawing blow molding, direct blowmolding, extrusion blow molding, to give final hollow molded articles.As a matter of course, the molded articles obtained by the moldingmachine such as an extrusion molding machine or an injection moldingmachine can be used as final hollow containers.

[0129] In production of such hollow molded articles, the polyester ofthe invention can be mixed with scrap resin generated in a productionprocess or polyester resin recovered from a market. Even if mixed withsuch recycled resin, the polyester resin of this invention is hardlydegraded, thus giving high-quality hollow molded articles.

[0130] Further, such containers can have a multi-layer structureprovided as an intermediate layer with a gas barrier resin layer such aspolyvinyl alcohol or polymethaxylylene diamine adipate or alight-shielding resin layer or a recycled polyester layer. Further,techniques such as vapor deposition and CVD (chemical vapor deposition)can be used to coat the container with a metal such as aluminum ordiamond-shaped carbon.

[0131] To improve the crystallizability of openings etc. of the moldedarticles, other resins such as polyethylene and inorganic nucleatingmaterials such as talc can also be added.

[0132] Further, the polyester resin of this invention can also beextruded through an extruding machine into a sheet-shaped material toprovide a sheet. The sheet is processed by vacuum molding, pressureforming, pattern embossing etc. and used as trays or containers forfoods and sundries, cups, blister packs, carrier tapes for electronicparts, and trays for delivery of electronic parts. Further, the sheetcan also be used as various kinds of cards.

[0133] These sheets can also have a multi-layer structure provided as anintermediate layer with a gas barrier resin layer, a light-shieldingresin layer or a recycled polyester layer as described above.

[0134] The polyester resin of this invention can also be mixed withrecycled resin. For the purpose of producing crystalline heat-resistantcontainers, other resins such as polyethylene and inorganic nucleatingagents such as talc can be added to improve crystallizability.

[0135] The polyester polymerized by using the polyester polymerizationcatalyst of this invention can be used in film. The method thereforinvolves melt-extrusion of the polyester and molding it through T-diesinto a sheet on a cooled rotating roll, to prepare a non-oriented sheet.In this process, techniques described in e.g. JP-B 6-39521 and JP-B6-45175 can be used for high-rate manufacture of the film. Using aplurality of extruders, the polyester can be formed by co-extrusion intoa multi-layer film having a core layer and skin layer each havingfunctions.

[0136] The polyester polymerized by using the polyester polymerizationcatalyst of this invention can be used as an oriented polyester film.The oriented polyester film can be obtained in a usual manner by drawingthe polyester 1.1- to 6-fold in at least one axial direction at atemperature ranging from the glass transition temperature tocrystallization temperature of the polyester.

[0137] For example, when a biaxially oriented polyester film is to beproduced, it is possible to employ a successive biaxial drawing methodwherein the polyester is subjected to monoaxial drawing in thelengthwise or width direction and then drawn in the perpendiculardirection, a method of simultaneous biaxial drawing in the lengthwiseand width directions, a method of using a linear motor for drivingsimultaneous biaxial drawing, and a multistage drawing method ofsubjecting polyester to drawing plural times in the same direction bywidth and lengthwise drawing, or lengthwise, width and lengthwisedrawing, or lengthwise, lengthwise and width drawing.

[0138] After drawing is finished, heat setting is preferably conductedat a temperature ranging from (the melting point minus 50° C.) to themelting point for 30 seconds or less, preferably 10 seconds or less,followed by lengthwise or width relaxation by 0.5 to 10% in order toreduce the thermal shrinkage of the film.

[0139] The thickness of the resultant oriented polyester film ispreferably 1 to 1000 μm, more preferably 5 to 500 μm and most preferably10 to 200 μm. When the thickness is 1 μl or less, the film is limp anddifficult to handle. On the other hand, when the thickness exceeds 1000μm, the film is too hard to handle.

[0140] For conferring various functions such as adhesion, moldreleasability, antistatic properties, infrared absorption, antimicrobialproperties and scuff resistance, a high-molecular resin may be appliedby coating onto the surface of the oriented polyester film. Further,inorganic and/or organic particles may be contained in only the coatinglayer, to form a smooth and highly transparent polyester film. Further,the film may be provided with an inorganic deposited layer to confervarious barrier functions against oxygen, water and oligomers or may beprovided with an electroconductive layer by sputtering to conferelectrical conductivity.

[0141] For improving handling properties such as smoothness, coveringproperties, abrasion resistance and winding properties, the surface ofthe film may be made uneven by adding inorganic and organic saltsparticles or heat-resistant polymeric resin particles in the process ofpolymerizing the polyester. These particles may be those subjected tosurface treatment or not subjected to surface treatment, and whensurface treatment is carried out, the surface treatment may behydrophilicity- or hydrophobicity-conferring treatment with inorganic ororganic compounds. For example, there is the case where particlessubjected to surface treatment for the purpose of improvingdispersibility etc. are preferably used.

[0142] The inorganic particles added include calcium carbonate, kaolin,talc, magnesium carbonate, barium carbonate, calcium sulfate, bariumsulfate, lithium phosphate, calcium phosphate, magnesium phosphate,aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, lithiumfluoride, sodium calcium alumisilicate etc.

[0143] The organic salt particles added include calcium oxalate andcalcium, barium, zinc, manganese or magnesium terephthalate.

[0144] The crosslinked polymer particles added include particles ofhomo- or copolymers consisting of vinyl monomers such as divinylbenzene, styrene, acrylic acid, methacrylic acid, acrylic acid andmethacrylic acid. In addition, organic particles such aspolytetrafluoroethylene, benzoguanamine resin, thermosetting resin,unsaturated polyester resin, thermosetting urea resin and thermosettingphenol resin may also be used.

[0145] The method of incorporating the inert particles into polyester asa substrate film includes, but is not limited to, (a) a method whereinthe inert particles are dispersed in a slurry form in diol as acomponent constituting the polyester and then the inert particle slurryis added to the reaction system for polymerization of the polyester, (b)a method wherein a slurry of the inert particles dispersed in water isadded to a melt polyester resin in a vented twin-screw extruder in thestep of melt-extrusion of polyester film, (c) a method wherein apolyester resin and the inert particles are kneaded in a molten state,and (d) a method wherein a polyester resin and a master resin of theinert particles are kneaded in a molten state.

[0146] In the case of the method of adding the inert particles to thepolymerization reaction system, the slurry of the inert particles indiol is added to the reaction system preferably having low meltviscosity before esterification reaction, transesterification reactionor polycondensation reaction. To prepare the slurry of the inertparticles in diol, physical dispersion treatment by a high-pressuredispersing machine or a bead mill or dispersion by sonication ispreferably conducted. For stabilizing the dispersed slurry, chemicaldispersion stabilizing treatment is used in combination depending on thetype of particles used.

[0147] In the dispersion stabilizing treatment in the case of e.g.inorganic oxide particles or crosslinked polymer particles havingcarboxyl groups on the surfaces of the particles, alkali compounds suchas sodium hydroxide, potassium hydroxide and lithium hydroxide are addedto the slurry, and by electrical repulsion, re-aggregation of theparticles can be prevented. In the case of calcium carbonate particlesand hydroxyapatite particles, sodium tripolyphosphate and potassiumtripolyphosphate are added preferably to the slurry.

[0148] Upon addition of the slurry of the inert particles in diol to thepolyester polymerization reaction system, heat treatment of the slurryat a temperature near to the boiling point of diol is preferable fordispersibility of the particles because heat shock (difference intemperature between the slurry and the polymerization reaction system)upon addition of the slurry to the polymerization reaction system can bereduced by the heat treatment.

[0149] These additives can be added at any arbitrary stages during orafter polyester polymerization or after production of polyester film,and the suitable stage at which the additives are added is varieddepending on the characteristics of the compound and the performancerequirement of polyester film.

[0150] Further, the polyester of the invention is excellent in thermalstability, so it is suitable that when the polyester is used to producefilms, film edges occurring in the drawing step or films not meetingstandards can be reutilized by melting.

[0151] The oriented polyester film of this invention is used preferablyas antistatic film, easily adhering film, film for cards, film for dummycans, film for agriculture, film for building materials, decorativematerials, wall papers, OHP film, printing film, film for ink jetrecording, film for sublimation transfer recording, film for laser beamprinter recording, film for electrophotographic recording, film forthermal transfer recording, film for heat-sensitive transfer recording,film for printed substrate wiring, film for membrane switching, film forplasma displays, film for tough panels, masking film, film forphotoengraving, X-ray film, photographic negative film, phase-differencefilm, polarizing film, polarizing film protection (TAC) film, protectfilm, photosensitive resin film, visual-field enlargement film, diffusersheet, reflective film, anti-glare film, electroconductive film,separator, film for UV shielding, and back-grind tapes.

[0152] For antistatic film, techniques described in Japanese Patent No.2952677 and JP-A 6-184337 can be used. For easily adhering film,techniques described in e.g. JP-B 7-108563, JP-A 10-235820 and JP-A11-323271 can be applied to the film of this invention, and for cards,techniques described in e.g. JP-A 10-171956 and JP-A 11-010815 can beapplied to the film of this invention. As a dummy can film in place of asheet-shaped cylinder described in e.g. JP-A 10-101103, the film of thisinvention can be used by printing a design thereon and then forming itin a cylindrical or semi-cylindrical form. For building materials,decorative sheets for building materials, and decorative materials, thefilm of this invention can be used as the substrate sheet described ine.g. JP-A 5-200927 or as the transparent sheet described in JP-A07-314630. For OHP (over head projector), the film of this invention canbe used as the transparent resin sheet described in JP-A 06-297831 or asthe transparent polymeric synthetic resin film described in JP-A08-305065. For ink jetting recording, the film of this invention can beused as the transparent base material described in e.g. JP-A 05-032037.For sublimation transfer recording, the film of this invention can beused as the transparent film described in e.g. JP-A 2000-025349. Forlaser beam printers or electrophotographic recording, the film of thisinvention can be used as the plastic film described in e.g. JP-A5-088400. For thermal transfer recording, the film of this invention canbe used in a method described in e.g. JP-A 07-032754, and forheat-sensitive recording, the film of this invention can be used in amethod described in e.g. JP-A 11-034503. For printed substrate, the filmof this invention can be used as the polyester film described in e.g.JP-A 06-326453. For membrane switching, the film of this invention canbe used in a method described in e.g. JP-A 05-234459. For opticalfilters (hot-wire filters, plasma displays), the film of this inventioncan be used in a method described in e.g. JP-A 11-231126. Fortransparent electroconductive film and touch panel, the film of thisinvention can be used in a method described in e.g. JP-A 11-224539. Formasking film, the film of this invention can be used in a methoddescribed in e.g. JP-A 05-273737. For photoengraving, the film of thisinvention can be used in a method described in e.g. JP-A 05-057844. Forphotographic negative film, the film of this invention can be used asthe polyethylene terephthalate film described in e.g. column No. (0123)in JP-A 06-167768. For phase-difference film, the film of this inventioncan be used as the film described in e.g. JP-A 2000-162419. Forseparator, the film of this invention can be used as the film describedin e.g. column No. (0012) in JP-A 11-209711. For UV shielding, the filmof this invention can be used as the polyester film described in e.g.JP-A 10-329291. An agricultural film can be obtained by applying thefilm of this invention to the polyethylene terephthalate film describedin e.g. JP-A 10-166534. An adhesive-backed sheet can be obtained byapplying the oriented polyester film of this invention to thepolyethylene terephthalate film described in e.g. JP-A 06-122856.

EXAMPLES

[0153] Hereinafter, the constitution and effect of this invention aredescribed in more detail by reference to the Examples, which are notintended to limit this invention.

Evaluation Methods

[0154] 1) Intrinsic Viscosity (IV)

[0155] Polyester was dissolved in a mixed solvent ofphenol/1,1,2,2-tetrachloroethane in the ratio of 6/4 (by weight) andmeasured at a temperature of 30° C.

[0156] 2) Acid Value (AV)

[0157] 0.1 g polyester polymer was heated and dissolved in 10 ml benzylalcohol, and measured by titration with 0.1 N NaOH in methanol/benzylalcohol (1/9).

[0158] 3) Content of Diethylene Glycol (DEG)

[0159] 0.1 g polyester was decomposed by heating at 250° C. in 2 mlmethanol and quantified by gas chromatography.

[0160] 4) Differential Scanning Calorimetry (DSC)

[0161] DSC2920 manufactured by TA Instruments was used for measurement.10.0 mg polyester was placed in an aluminum pan and heated to 280° C. atan increasing temperature of 50° C./min., and when 280° C. was reached,the sample was kept for 1 minute and immediately quenched in liquidnitrogen. Thereafter, the sample was heated from room temperature to300° C. at an increasing temperature of 20° C./min., during which thecrystallization temperature Tc1 and melting point Tm were determined.When 300° C. was reached, the sample was kept at that temperature for 2minutes and then cooled at a decreasing temperature of 10° C./min.,during which the crystallization temperature Tc2 was determined. Tc1, Tmand Tc2 were maximum peak temperatures respectively.

[0162] 5) Color Tone

[0163] When predetermined torque was reached in melt polymerization,nitrogen was introduced into the autoclave and returned to normalpressure, and the polycondensation reaction was terminated. Thereafter,the polymer was quenched under slight pressure by discharging it in astrand form into cold water and thereafter maintained for about 20seconds in cold water, and cut into cylindrical resin chips of about 3mm in length and about 2 mm in diameter. The resin chips thus obtainedwere air-dried for about one day on a filter paper at room temperatureand used in color measurement. In color measurement, the PET resin chipshaving an IV of about 0.65 dl/g obtained by melt polymerization weremeasured for Hunter's L value, a value and b value by a color differencemeter (Model TC-1500MC-88, manufactured by Tokyo Denshoku Co., Ltd.).

[0164] 6) Solution Haze (Haze)

[0165] Melt-polymerized PET resin chips having an IV of about 0.65 dl/gwere dissolved in a mixed solvent ofp-chlorophenol/1,1,2,2-tetrachloroethane in the ratio of 3/1 (by weight)to give 8 g/100 ml solution which was then measured at room temperatureby a turbidity meter model NDH2000 manufactured by Nippon Denshoku Co.,Ltd. In this measurement, diffused transmitted light (DF) and totaltransmitted light (TT) in the solution were measured by a cell of 1 cmin length according to JIS standards JIS-K7105, and the haze (%) wasdetermined according to the following equation:

Haze (%)=(DF/TT)×100

[0166] 7) Thermal Stability Parameter (TS)

[0167] TS was determined as follows: 1 g of melt-polymerized PET resinchips having an IV of about 0.65 dl/g ([IV]_(i) before the melting test)were placed in a glass test tube having an internal diameter of about 14mm and then vacuum-dried at 130° C. for 12 hours, and the glass testtube was connected to a vacuum line where the replacement of theatmosphere by nitrogen was conducted five or more times by introducingnitrogen under reduced pressure, to achieve a nitrogen atmosphere at 100mmHg in the glass test tube which was then was sealed. This test tubewas dipped in a salt bath at 300° C. and maintained for 2 hours in amolten state, and the sample was removed, frozen and milled, andvacuum-dried to determine the IV ([IV]_(f1) after the melting test).From the [IV]_(f1), TS was calculated using the equation below. Theequation is from a previous report (Kamiyama et al.: Journal of Societyof Rubber Industry, Japan, vol. 63, no. 8, p. 497, 1990).

TS=0.245 {[IV]_(f1) ^(−1.47)−[IV]_(i) ^(−1.47)}

[0168] 8) Thermal Oxidation Stability Parameter (TOS)

[0169] Melt-polymerized PET resin chips having an IV of about 0.65 dl/gwere frozen and milled to give powders of 20 meshes or less. The powderswere vacuum-dried at 130° C. for 12 hours, and 300 mg of the powderswere placed in a glass test tube having an inner diameter of about 8 mmand a length of about 140 mm, vacuum-dried at 70° C. for 12 hours, andheated at 230° C. for 15 minutes in air dried by connecting a dry tubecontaining silica gel to an upper part of the test tube dipped in a saltbath. From the IV of the PET after this heating, TOS was determinedaccording to the same equation shown later as for TS above. In theequation, [IV]_(i) and [IV]_(f3) refer to IV (dl/g) before and after theheating test respectively. Freezing and milling was conducted using afreezer mill (6750 model, US Spex Inc.). About 2 g resin chips and aspecial impactor were placed in a special cell, and the cell was set inthe mill, and liquid nitrogen was introduced into the mill andmaintained for about 10 minutes, and the sample was milled for 5 minutesat a rate of 10 (at which the impactor was inverted about 20 times persecond).

TOS=0.245 {[IV]_(f3) ^(−1.47)−[IV]_(i) ^(−1.47)}

[0170] 9) Hydrolytic Stability Parameter (HS)

[0171] Melt-polymerized PET resin chips having an intrinsic viscosity ofabout 0.65 dl/g ([IV]_(i) before the test) were frozen and milled in themanner as in 8) above, to give powders of 20 meshes or less which werethen vacuum-dried at 130° C. for 12 hours. A hydrolysis test wasconducted using a mini-color unit (Type M12. ELB, manufactured by TexamGiken Co., Ltd.). 1 g of the powders, together with 100 ml purifiedwater, were placed in a special stainless steel beaker, and a specialstirring blade was added to it, and in a closed system, the beaker wasset in the mini-color unit and stirred under heating at 130° C. underpressure for 6 hours. After the test, the PET was collected on a glassfilter, vacuum-dried and then measured for IV ([IV]_(f2)), to determinethe hydrolysis stability parameter (HS) by using the equation below.

HS=0.245 {[IV]_(f2) ⁻1.47−[IV]_(i) ^(−1.47)}

[0172] 10) Oligomer Acid Value (AV₀)

[0173] The oligomer is milled and dried under reduced pressure at 110°C. for 15 hours or more. 20 ml pyridine is added to about 1 g of theaccurately weighed sample. The sample is dissolved by boiling for 15minutes. After dissolution, 10 ml purified water is added thereto, andthe sample solution is left and cooled. The sample is titrated with 1/10N NaOH with phenolphthalein as an indicator. A blank sample free of thesample is also examined in the same procedure. If the oligomer is notdissolved in pyridine, it is examined in benzyl alcohol.

[0174] AV₀ (eq/ton) is calculated according to the following equation:

AV ₀=(A−B)×0.1×f×1000/W

[0175] wherein A=titration volume (ml), B=titration volume (ml) of theblank, f=factor of NaOH, W=weight of the sample (g).

[0176] 11) Oligomer OH Value (OHV₀)

[0177] The oligomer is milled and dried under reduced pressure at 110°C. for 15 hours or more. 20 ml pyridine is added to about 0.5 g of theaccurately weighed sample, and 10 ml of an acetylating agent (anhydrousacetic acid-pyridine solution, 0.5 mol-%/L) is added thereto. After thesample solution is dipped in a water bath at 95° C. or more for 1.5hours, 10 ml purified water is added thereto, and the sample solution isleft and cooled. The sample is titrated with 1/5 N NaOH withphenolphthalein as an indicator. A blank sample free of the sample isalso examined in the same procedure.

[0178] OHV₀ (eq/ton) is calculated according to the following equation:

OHV ₀={(B−A)×0.2×f×1000/W}+AV ₀

[0179] wherein A=titration volume (ml), B=titration volume (ml) of theblank, f=factor of 1/5 NaOH, W=weight of the sample (g).

[0180] 12) Calculation of Pn

Pn (degree of polymerization)=[MW+26−88×{OHV ₀/(AV ₀ +OHV ₀)}]/(192+44E)

[0181] wherein MW (molecular weight (g/mol))=10⁶×2/(AV₀+OHV₀)

E=DEG/(EG+DEG)

[0182] wherein E is the molar fraction of diethylene glycol formed, DEGis the number of moles of diethylene glycol in the polymer, and EG isthe number of moles of ethylene glycol.

[0183] 13) Calculation of the Degree of Esterification (Es (%))

Degree of esterification=[1−AV ₀ /{Pn(AV ₀ +OHV ₀)}]×100

[0184] 14) Measurement of Grain Size

[0185] The particles were dispersed by sonication in a solvent notdissolving them, and their grain size was measured by use of MicrotracFRA-9220 (Nikkiso). Aluminum trisacetylacetonate powder was dispersed inNisseki Mitsubishi Super Mulpass 5K20J2 and measured for its grain size.

[0186] 15) Strength and Elongation of Drawn Yarn

[0187] Strength and elongation were measured 5 times respectively byTensilone (Orientec) under the conditions of a gauge length of 200 mmand a crosshead speed of 200 mm/min., and the average was used forevaluation.

[0188] 16) Orientation of Drawn Yarn

[0189] The average (n=5) was determined on the basis of retardation andfiber diameter by a polarizing microscope equipped with a Berekcompensator.

[0190] 17) Density of Drawn Yarn

[0191] The average density of samples (n=3) was determined at 30° C. ina density gradient tube consisting of a mixture of calcium nitrate.4H₂Oand purified water.

[0192] 18) Color Tone After Interweaving and Refining

[0193] Eight samples were piled up and measured by a spectrometric colormeasuring instrument CM-3700 manufactured by Minolta Co., Ltd., todetermine L*, a*, and b*.

[0194] 19) Haze (Haze-%)

[0195] Determined by a haze meter model NDH2000 manufactured by NipponDenshoku Co., Ltd.

[0196] 20) Acetaldehyde Content

[0197] The sample and distilled water were introduced in a ratio ofsample/distilled water=1 g/2 ml into a glass ampoule flushed withnitrogen, and the upper part of the ampoule was melt-sealed, and thesample was extracted at 160° C. for 2 hours, and after cooling, theconcentration of acetaldehyde in the extract was measured byhigh-sensitive gas chromatography and expressed in ppm.

[0198] 21) Strength and Elongation of Biaxially Drawn Film

[0199] The film was cut into strips of 10 mm in width and 180 mm inlength and set in a tensile testing machine (RTM100, manufactured byToyo Baldwin) with the distance between chucks adjusted to 100 mm, andmeasured at a drawing rate of 100 mm/min. under the environment of 23°C.×65% RH.

[0200] 22) Specific Resistance of Melt Polymer (ρi)

[0201] Two electrode plates were placed in polyester melted at 275° C.,and the current (i₀) upon application of a voltage of 120 V is measured,and the specific resistance ρi is determined according to the followingequation:

ρi (Ω·cm)=A/1×V/i ₀

[0202] wherein A=the area of the electrode (cm²), 1=the distance betweenthe electrodes (cm), V=voltage (V).

[0203] 23) Color Tone of Hollow Molded Article

[0204] A sample is cut off from the body (wall thickness, about 0.4 mm)of a 1500-ml bottle obtained by biaxially drawing blow molding, and thenmeasured for its Hunter's L value, a value and b value by a colordifference meter Model TC-1500MC-88 (Tokyo Denshoku Co., Ltd.).

Synthesis Example of Polyester Example 1

[0205] To a mixture of bis(2-hydroxyethyl) terephthalate and oligomersproduced in a usual manner from high-purity terephthalic acid andethylene glycol were added 13 g/l aluminum chloride as apolycondensation catalyst in ethylene glycol in an amount of 0.015 mol-%in terms of aluminum atom relative to the acid component in thepolyester and 10 g/l Irganox 1425 (Ciba Specialty Chemicals Inc.) inethylene glycol in an amount of 0.02 mol-% in terms of Irganox 1425relative to the acid component, and the mixture was stirred at 245° C.for 10 minutes in a nitrogen atmosphere at normal pressure. Then, thetemperature was increased to 275° C. over 50 minutes while the pressurein the reaction system was gradually reduced to 13.3 Pa (0.1 Torr), andthe polycondensation reaction was further conducted at 275° C. at 13.3Pa.

[0206] The polyethylene terephthalate (PET) having an IV of 0.65 dl/g,obtained in the polycondensation described above, was formed in a usualmanner into chips. Measurement results such as the time necessary forthe polycondensation reaction and the intrinsic viscosity, acid valueand color tone of PET after polycondensation are shown in Table 1.

[0207] The PET resin chips were examined in a melt test to determine thethermal stability parameter (TS).

[0208] The chipped PET resin was milled in a usual manner, and thepowder was examined in a hydrolytic test and a thermal oxidationstability test to determine the hydrolytic stability (HS) parameter andthe thermal oxidation stability (TOS) parameter, and these results areshown in Table 1.

Examples 2 and 3

[0209] PET was prepared in the same manner as in Example 1 except thatthe type of the catalyst used was changed. Evaluation was also conductedin the same manner as in Example 1. The composition of the catalyst usedand evaluation results are shown in Table 1. A catalyst componentlithium acetate.2H₂O was added in the form of 50 g/l solution inethylene glycol in the amount shown in Table 1, which is expressed interms of lithium atom relative to the acid component in PET.

Comparative Example 1

[0210] Production of PET was attempted in the same manner as in Example1 except that Irganox 1425 was not used as a polycondensation catalystcomponent. The polycondensation reaction was performed for 180 minutes,but a sufficient degree of polymerization could not be reached.

Comparative Example 2

[0211] The same procedure as in Example 1 was repeated except thatantimony trioxide was used in an amount of 0.05 mol-% in terms ofantimony atom relative to the acid component in PET. The evaluationresults are also shown in Table 1.

Evaluation Results

[0212] As can be seen from the results in Table 1, the catalysts of thisinvention have a high polymerization activity, that is, thepolycondensation time required for the intrinsic viscosity to reach thepractical value of 0.65 dl/g is short, and the resultant polyester isexcellent in color tone, has low TS and is excellent in thermalstability and superior in thermal oxidation stability and hydrolyticstability.

[0213] On the other hand, the catalyst not using the phosphorus compoundof this invention is poor in polymerization activity, while the catalystusing antimony trioxide has a high polymerization activity, but problemssuch as gray discoloration and insoluble particles as described aboveare inevitable.

Example 4

[0214] A heat transfer medium-circulating 2-L stainless steel autoclaveequipped with a stirrer was charged with high-purity terephthalic acidand ethylene glycol in the molar ratio of 1:2, and triethylamine wasadded in an amount of 0.3 mol-% relative to the acid component, and themixture was subjected to esterification reaction for 110 minutes at apressure of 0.25 MPa at 250° C. while water was distilled away from thesystem, whereby a mixture of bis(2-hydroxyethyl) terephthalate (BHET)and oligomers (referred to hereinafter as BHET mixture) having a degreeof esterification of 95% or more was obtained. To this BHET mixture wereadded 2.5 g/l aluminum acetylacetonate as a polycondensation catalyst inethylene glycol in an amount of 0.014 mol-% in terms of aluminum atomrelative to the acid component in the polyester and 100 g/l Irganox 1425(Ciba Specialty Chemicals Inc.) in ethylene glycol in an amount of 0.01mol-% in terms of Irganox 1425 relative to the acid component, and themixture was stirred at 250° C. for 15 minutes in a nitrogen atmosphereat normal pressure. Then, the temperature was increased to 275° C. over60 minutes while the pressure in the reaction system was graduallyreduced to 66.5 Pa (0.5 Torr), and the polycondensation reaction wasfurther conducted at 275° C. at 66.5 Pa. The polycondensation timenecessary for obtaining PET having an IV of 0.61 dl/g was 123 minutes,indicating that this catalyst had a practical catalytic activity. Thephysical properties of the resultant PET are shown in Table 2.

Example 5 Preparation Example 1 for Solution of Aluminum HydroxideChloride in Mixed Solvent of Water/Ethylene Glycol

[0215] Ethylene glycol was added to about 10% (in terms of A1203)aqueous solution of polyaluminum chloride represented by the structuralformula [Al₂(OH)_(n)Cl_(6-n)]_(m) (n is about 3, m≦10) in the ratio ofabout 50:1 by volume and stirred to prepare a solution.

Polymerization Example of Polyester

[0216] Polyester was polymerized in the same manner as in Example 4except that the solution of polyaluminum chloride in a mixed solvent ofwater/ethylene glycol was added as a polycondensation catalyst in anamount of 0.014 mol-% in terms of aluminum atom relative to the acidcomponent in the polyester and 100 g/l Irganox 1425 (Ciba SpecialtyChemicals Inc.) in ethylene glycol in an amount of 0.01 mol-% in termsof Irganox 1425 relative to the acid component. The polymerization timewas 119 minutes, and the IV of the resulting PET was 0.61 dl/g. Otherphysical properties are shown in Table 2.

Example 6 Preparation Example 2 for Solution of Aluminum HydroxideChloride in Mixed Solvent of Water/Ethylene Glycol

[0217] Ethylene glycol was added to about 10% (in terms of Al₂O₃)aqueous suspension of basic aluminum chloride represented by thestructural formula [Al₂(OH)_(n)Cl_(6-n)]_(m) (n is about 5) in the ratioof about 50:1 by volume and stirred to prepare a solution.

Polymerization Example of Polyester

[0218] Polyester was polymerized in the same manner as in Example 4except that the solution of basic aluminum chloride in a mixed solventof water/ethylene glycol was added as a polycondensation catalyst in anamount of 0.014 mol-% in terms of aluminum atom relative to the acidcomponent in the polyester and 100 g/l Irganox 1425 (Ciba SpecialtyChemicals Inc.) in ethylene glycol in an amount of 0.01 mol-% in termsof Irganox 1425 relative to the acid component. The polymerization timewas 125 minutes, and the IV of the resulting PET was 0.60 dl/g. Otherphysical properties are shown in Table 2.

Example 7

[0219] Polyester was synthesized in the same manner as in Example 4except that 5 g/l aluminum chloride.6H₂O in ethylene glycol was added asa polycondensation catalyst in an amount of 0.014 mol-% in terms ofaluminum atom relative to the acid component in the polyester and 100g/l Irganox 1425 (Ciba Specialty Chemicals Inc.) in ethylene glycol inan amount of 0.01 mol-% in terms of Irganox 1425 relative to the acidcomponent. The polymerization time was 121 minutes, and the IV of theresulting PET was 0.60 dl/g. Other physical properties are shown inTable 2.

Example 8

[0220] A heat transfer medium-circulating 2-L stainless steel autoclaveequipped with a stirrer was charged with high-purity terephthalic acidand ethylene glycol in the molar ratio of 1:2, and triethylamine wasadded in an amount of 0.3 mol-% relative to the acid component, and 8g/l Irganox 1222 (Ciba Specialty Chemicals Inc.) in ethylene glycol inan amount of 0.03 mol-% in terms of Irganox 1222 relative to the acidcomponent, and the mixture was subjected to esterification reaction for110 minutes at a pressure of 0.25 MPa at 250° C. while water wasdistilled away from the system, whereby a mixture of bis(2-hydroxyethyl)terephthalate (BHET) and oligomers (referred to hereinafter as BHETmixture) having a degree of esterification of 95% or more was obtained.To this BHET mixture were added the above polyaluminum chloride solutionas a polycondensation catalyst in a mixed solvent of water/ethyleneglycol in an amount of 0.014 mol-% in terms of aluminum atom relative tothe acid component in the polyester and 10 g/l of magnesium acetate.4H₂Oin ethylene glycol in an amount of 0.01 mol-% in terms of magnesium atomrelative to the acid component, and the mixture was stirred at 250° C.for 15 minutes in a nitrogen atmosphere at normal pressure. Then, thetemperature was increased to 275° C. over 60 minutes while the pressurein the reaction system was gradually reduced to 66.5 Pa (0.5 Torr), andthe polycondensation reaction was further conducted at 275° C. at 66.5Pa. The polycondensation time necessary for obtaining PET having an IVof 0.60 dl/g was 123 minutes, indicating that this catalyst had apractical catalytic activity. The physical properties of the resultantPET are shown in Table 2.

Comparative Example 3

[0221] Polyester was polymerized in the same manner as in Example 4except that antimony trioxide was added as a polycondensation catalystin an amount of 0.04 mol-% in terms of antimony atom relative to theacid component in the polyester. The polymerization time was 112minutes, and the IV of the resulting PET was 0.61 dl/g. Other physicalproperties are shown in Table 2.

Example 9 Preparation Example for Solution of Basic Aluminum Acetate inMixed Solvent of Water/Ethylene Glycol

[0222] Basic aluminum acetate (hydroxy aluminum diacetate, manufacturedby ALDRICH) was added to deionized water at a concentration of lg/50 mland stirred for 12 hours at ordinary temperature. Thereafter, thesolution was stirred at about 70° C. for 6 hours to give a transparentaqueous solution. Ethylene glycol was added to this aqueous solution inthe ratio of 3:1 by volume and stirred at room temperature for 6 hoursto prepare a catalyst solution.

Polymerization Example of Polyester

[0223] A heat transfer medium-circulating 2-L stainless steel autoclaveequipped with a stirrer was charged with high-purity terephthalic acidand ethylene glycol in the molar ratio of 1:2, and triethylamine wasadded in an amount of 0.3 mol-% relative to the acid component, and themixture was subjected to esterification reaction for 115 minutes at apressure of 0.25 MPa at 250° C. while water was distilled away from thesystem, whereby a mixture of bis(2-hydroxyethyl) terephthalate (BHET)and oligomers (referred to hereinafter as BHET mixture) having a degreeof esterification of 95% or more was obtained. To this BHET mixture wereadded the above basic aluminum acetate solution as a polycondensationcatalyst in a mixed solvent of water/ethylene glycol in an amount of0.014 mol-% in terms of aluminum atom relative to the acid component inthe polyester and 100 g/l Irganox 1425 (Ciba Specialty Chemicals Inc.)in ethylene glycol in an amount of 0.01 mol-% in terms of Irganox 1425relative to the acid component, and the mixture was stirred at 250° C.for 15 minutes in a nitrogen atmosphere at normal pressure. Then, thetemperature was increased to 275° C. over 60 minutes while the pressurein the reaction system was gradually reduced to 66.5 Pa (0.5 Torr), andthe polycondensation reaction was further conducted at 275° C. at 66.5Pa. The polycondensation time necessary for obtaining PET having an IVof 0.61 dl/g was 132 minutes, indicating that this catalyst had apractical catalytic activity. The physical properties of the resultantPET are shown in Table 3.

Example 10 Preparation Example 1 for Solution of Basic Aluminum Acetatein Ethylene Glycol

[0224] While the above basic aluminum acetate in a mixed solvent ofwater/ethylene glycol was stirred at 90 to 110° C. for several hours,water was distilled away. As a result, a solution of basic aluminumacetate at a concentration of about 6.5 g/l in ethylene glycol wasobtained.

Polymerization Example of Polyester

[0225] Polyester was polymerized in the same manner as in Example 9except that the solution of basic aluminum acetate in ethylene glycolwas added as a polycondensation catalyst in an amount of 0.014 mol-% interms of aluminum atom relative to the acid component in the polyesterand 100 g/l Irganox 1425 (Ciba Specialty Chemicals Inc.) in ethyleneglycol was added in an amount of 0.01 mol-% in terms of Irganox 1425relative to the acid component. The polymerization time was 133 minutes,and the IV of the resulting PET was 0.60 dl/g. Other physical propertiesare shown in Table 3.

Example 11 Preparation Example 2 for Solution of Basic Aluminum Acetatein Ethylene Glycol

[0226] Basic aluminum acetate (CH₃COOAl(OH)₂.1/3H₃BO₃, manufactured byALDRICH) was stirred in ethylene glycol at about 70° C. for 5 hours, togive a solution thereof at a concentration of about 5 g/l in ethyleneglycol.

Polymerization Example of Polyester

[0227] Polyester was polymerized in the same manner as in Example 1except that the above 5 g/l basic aluminum acetate solution in ethyleneglycol was added as a polycondensation catalyst in an amount of 0.014mol-% in terms of aluminum atom relative to the acid component in thepolyester and 10 g/l Irganox 1425 (Ciba Specialty Chemicals Inc.) inethylene glycol in an amount of 0.01 mol-% in terms of Irganox 1425relative to the acid component. The polymerization time was 90 minutes,and the IV of the resulting PET was 0.65 dl/g. The IV of the resultingPET was 2 equivalents/ton, the Tm was 256° C., the L value was 68.9, thea value was −2.3, and the b value was 4.2.

Example 12 Preparation Example for Solution of Aluminum Lactate inEthylene Glycol

[0228] About 67 g/l aqueous aluminum lactate solution was prepared atnormal temperatures. Thereafter, ethylene glycol was added thereto, andwater was distilled away by heating at about 100° C., whereby about 29g/l solution thereof in ethylene glycol was obtained.

Polymerization Example of Polyester

[0229] Polyester was polymerized in the same manner as in Example 9except that the solution of aluminum lactate in ethylene glycol wasadded as a polycondensation catalyst in an amount of 0.014 mol-% interms of aluminum atom relative to the acid component in the polyesterand 100 g/l Irganox 1425 (Ciba Specialty Chemicals Inc.) in ethyleneglycol in an amount of 0.01 mol-% in terms of Irganox 1425 relative tothe acid component. The polymerization time was 124 minutes, and the IVof the resulting PET was 0.60 dl/g. Other physical properties are shownin Table 3.

Example 13

[0230] A heat transfer medium-circulating 2-L stainless steel autoclaveequipped with a stirrer was charged with high-purity terephthalic acidand ethylene glycol in the molar ratio of 1:2, and triethylamine wasadded in an amount of 0.3 mol-% relative to the acid component, and themixture was subjected to esterification reaction at a pressure of 0.25MPa at 250° C. while water was distilled away from the system, whereby aBHET mixture having a degree of esterification of 95% or more wasobtained. To this BHET mixture were added 2.5 g/l aluminumtrisacetylacetonate solution as a polycondensation catalyst in ethyleneglycol in an amount of 0.007 mol-% in terms of aluminum atom relative tothe acid component in the polyester and 100 g/l Irganox 1425 (CibaSpecialty Chemicals Inc.) in ethylene glycol in an amount of 0.005 mol-%in terms of Irganox 1425 relative to the acid component, and further 35g/l potassium titanyl oxalate.2H₂O in ethylene glycol in an amount of0.0004 mol-% in terms of titanium atom relative to the acid component,and the mixture was stirred at 250° C. for 15 minutes in a nitrogenatmosphere at normal pressure. Then, the temperature was increased to275° C. over 60 minutes while the pressure in the reaction system wasgradually reduced to 66.5 Pa (0.5 Torr), and the polycondensationreaction was further conducted at 275° C. at 66.5 Pa. Thepolycondensation time necessary for obtaining PET having an IV of 0.61dl/g was 93 minutes, indicating that this catalyst had a highercatalytic activity than a usual antimony catalyst. The AV of theresulting PET was 2 equivalents/ton, the Tm was 257° C., the L value was67.7, the a value was −1.7, and the b value was 3.7.

Example 14

[0231] PET was polymerized in the same manner as in Example 13 exceptthat 2.5 g/l aluminum trisacetylacetonate solution in ethylene glycolwas added as a polycondensation catalyst in an amount of 0.007 mol-% interms of aluminum atom relative to the acid component in the polyesterand 100 g/l Irganox 1425 (Ciba Specialty Chemicals Inc.) in ethyleneglycol in an amount of 0.005 mol-% in terms of Irganox 1425 relative tothe acid component, and further, a composite oxide of titaniumoxide/silicon oxide (titanium/silicon=9/1) was added in an amount of 4ppm relative to the polyester to be obtained by polymerization. Thepolycondensation time necessary for obtaining PET having an IV of 0.61dl/g was 109 minutes, indicating that this catalyst had a practicalcatalytic activity. The Tm of the resulting PET was 256° C., the L valuewas 67.7, the a value was −1.5, and the b value was 3.3.

Example 15

[0232] A heat transfer medium-circulating 2-L stainless steel autoclaveequipped with a stirrer was charged with high-purity terephthalic acidand ethylene glycol in the molar ratio of 1:2, and triethylamine wasadded in an amount of 0.3 mol-% relative to the acid component, and 8g/l aqueous germanium dioxide solution was added in an amount of 0.006mol-% in terms of germanium atom relative to the acid component in thepolyester, and the mixture was subjected to esterification reaction for110 minutes at a pressure of 0.25 MPa at 250° C. while water wasdistilled away from the system, whereby a BHET mixture having a degreeof esterification of 95% or more was obtained. To this BHET mixture wereadded 2.5 g/l aluminum trisacetylacetonate solution as apolycondensation catalyst in ethylene glycol in an amount of 0.007 mol-%in terms of aluminum atom relative to the acid component in thepolyester and 100 g/l Irganox 1425 in ethylene glycol in an amount of0.005 mol-% in terms of Irganox 1425 relative to the acid component, andthe mixture was stirred at 250° C. for 15 minutes in a nitrogenatmosphere at normal pressure. Then, the temperature was increased to275° C. over 60 minutes while the pressure in the reaction system wasgradually reduced to 66.5 Pa (0.5 Torr), and the polycondensationreaction was further conducted at 275° C. at 66.5 Pa. Thepolycondensation time necessary for obtaining PET having an IV of 0.61dl/g was 129 minutes, indicating that this catalyst had a practicalcatalytic activity. The AV of the resulting PET was 2 equivalents/ton,the Tm was 255° C., the L value was 66.3, the a value was −1.4, and theb value was 2.4.

Example 16

[0233] A heat transfer medium-circulating 2-L stainless steel autoclaveequipped with a stirrer was charged with high-purity terephthalic acidand ethylene glycol in the molar ratio of 1:2, and triethylamine wasadded in an amount of 0.3 mol-% relative to the acid component, and 8g/l Irganox 1222 in ethylene glycol was added in an amount of 0.03 mol-%in terms of Irganox 1222 relative to the acid component in thepolyester, and the mixture was subjected to esterification reaction for115 minutes at a pressure of 0.25 MPa at 250° C. while water wasdistilled away from the system, whereby a BHET mixture having a degreeof esterification of 95% or more was obtained. To this BHET mixture wereadded 2.5 g/l aluminum trisacetylacetonate solution as apolycondensation catalyst in ethylene glycol in an amount of 0.014 mol-%in terms of aluminum atom relative to the acid component in thepolyester and 14 g/l antimony atom in ethylene glycol in an amount of0.01 mol-% in terms of antimony atom relative to the acid component, andthe mixture was stirred at 250° C. for 15 minutes in a nitrogenatmosphere at normal pressure. Then, the temperature was increased to275° C. over 60 minutes while the pressure in the reaction system wasgradually reduced to 66.5 Pa (0.5 Torr), and the polycondensationreaction was further conducted at 275° C. at 66.5 Pa. Thepolycondensation time necessary for obtaining PET having an IV of 0.61dl/g was 115 minutes, indicating that this catalyst had a practicalcatalytic activity. The AV of the resulting PET was 3 equivalents/ton,the Tm was 256° C., the L value was 64.8, the a value was −0.7, and theb value was 1.9.

Example 17

[0234] A heat transfer medium-circulating 2-L stainless steel autoclaveequipped with a stirrer was charged with high-purity terephthalic acidand ethylene glycol in the molar ratio of 1:2, and triethylamine wasadded in an amount of 0.3 mol-% relative to the acid component, and themixture was subjected to esterification reaction at a pressure of 0.25MPa at 245° C. while water was distilled away from the system, whereby amixture of bis(2-hydroxyethyl) terephthalate (BHET) and oligomers(referred to hereinafter as BHET mixture) shown in Table 4 was obtained.To this BHET mixture were added 2.5 g/l aluminum trisacetylacetonatesolution in ethylene glycol in an amount of 0.008 mol-% in terms ofaluminum atom relative to the acid component in the polyester and 10 g/lIrganox 1425 (Ciba Specialty Chemicals Inc.) in ethylene glycol in anamount of 0.012 mol-% in terms of Irganox 1425 relative to the acidcomponent, and the mixture was stirred at 245° C. for 15 minutes in anitrogen atmosphere at normal pressure. Then, the temperature wasincreased to 275° C. over 60 minutes while the pressure in the reactionsystem was gradually reduced to 13.3 Pa (0.1 Torr), and thepolycondensation reaction was further conducted at 275° C. at 13.3 Pa.The PET resin chips obtained by the polycondensation were examined forvarious physical properties. The results are shown in Table 5.

Examples 18 and 19

[0235] A polymer was polymerized in the same manner as in Example 17except that the esterification termination time was changed. Thephysical properties of the BHET mixture are shown in Table 4, and thepolymerization results are shown in Table 5.

Example 20

[0236] A polymer was polymerized in the same manner as in Example 18except that the ratio of ethylene glycol/high-purity terephthalic acid(EG/TPA) added was changed. The physical properties of the BHET mixtureare shown in Table 4, and the polymerization results are shown in Table5.

Example 21

[0237] A polymer was polymerized in the same manner as in Example 18except that the amount of the catalyst added was changed. The physicalproperties of the BHET mixture are shown in Table 4, and thepolymerization results are shown in Table 5.

Examples 22 and 23

[0238] A polymer was polymerized in the same manner as in Example 17except that Irganox 1222 (Ciba Specialty Chemicals Inc.) was used as thephosphorus compound, and the amount of the catalyst added was changed asshown in Table 4. The physical properties of the BHET mixture uponaddition of the phosphorus compound are shown in Table 4, and thepolymerization results are shown in Table 5. In Example 23, Irganox 1222(Ciba Specialty Chemicals Inc.) was added at the time of charging beforeesterification reaction.

Example 24

[0239] A polymer was polymerized in the same manner as in Example 18except that 30 g/l aluminum trisacetylacetonate slurry having an averageparticle diameter of 5.6 μm in ethylene glycol was added. The physicalproperties of the BHET mixture are shown in Table 4, and thepolymerization results are shown in Table 5. Sedimentation of the slurrywas at a practically unproblematic level.

Example 25

[0240] A polymer was polymerized in the same manner as in Example 18except that aluminum trisacetylacetonate and the powder of thephosphorus compound were wrapped with a polyester film and added. Thephysical properties of the BHET mixture are shown in Table 4, and thepolymerization results are shown in Table 5.

Example 26

[0241] A catalyst solution was prepared by dissolving 0.24 g aluminumtrisacetylacetonate and 0.36 g Irganox 1425 (Ciba Specialty ChemicalsInc.) in 100 ml ethylene glycol. A polymer was polymerized in the samemanner as in Example 18 except that the catalyst solution was added inan amount of 0.014 mol-% in terms of aluminum atom relative to the acidcomponent in the polyester. The polymerization time and the physicalproperties of the polymer were almost the same as in the case where thealuminum compound and the phosphorus compound were added separately.

Example 27

[0242] A stainless steel autoclave equipped with a stirrer was chargedwith high-purity terephthalic acid and ethylene glycol in the molarratio of 1:2, and triethylamine was added in an amount of 0.3 mol-%relative to the acid component, and Irganox 1222 (Ciba SpecialtyChemicals Inc.) was added in an amount of 0.03 mol-% in terms of Irganox1222 relative to the acid component, and the mixture was subjected toesterification reaction for 110 minutes at a pressure of 0.25 MPa at260° C. while water was distilled away from the system, whereby a BHETmixture was obtained. To this BHET mixture was added 3 g/l aluminumtrisacetylacetonate in ethylene glycol in an amount of 0.014 mol-% interms of aluminum atom relative to the acid component in the polyester,and the mixture was stirred at 260° C. for 20 minutes in a nitrogenatmosphere at normal pressure. Then, the temperature was increased to280° C. over 50 minutes while the pressure in the reaction system wasgradually reduced to 13.3 Pa (0.1 Torr), and the polycondensationreaction was further conducted at 280° C. at 13.3 Pa. Thepolycondensation reaction was carried out for 150 minutes, whereby PEThaving an IV of 0.61 dl/g was obtained.

Example 28

[0243] To a mixture of bis(2-hydroxyethyl)terephthalate and oligomersproduced in a usual manner were added aluminum trisacetylacetonateslurry as a polycondensation catalyst in ethylene glycol in an amount of0.07 mol-% in terms of aluminum atom relative to the acid component inthe polyester and 10 g/l Irganox 1425 (Ciba Specialty Chemicals Inc.) inan amount of 0.03 mol-% in terms of Irganox 1425 relative to the acidcomponent, and the mixture was stirred at 245° C. for 10 minutes in anitrogen atmosphere at normal pressure. Then, the temperature wasincreased to 275° C. over 50 minutes while the pressure in the reactionsystem was gradually reduced to 13.3 Pa (0.1 Torr), and thepolycondensation reaction was further conducted at 275° C. at 13.3 Pa.PET having an IV of 0.62 dl/g was obtained.

Example 29

[0244] 2.5 g powder of aluminum trisacetylacetonate (99.9% or morepurity, manufactured by Kanto Kagaku Co., Ltd.) and 1000 ml ethyleneglycol were introduced into a glass vessel and stirred under heatingwith a hot stirrer set at a temperature of 70° C. After the powder wascompletely dissolved, the solution was returned to room temperature. Thesolution was stored at 50° C.

[0245] Separately, 100 g powder of Irganox 1425 (Ciba SpecialtyChemicals Inc.) and 1000 ml ethylene glycol were introduced into a glassvessel and stirred at room temperature for 24 hours or more, wherebyIrganox 1425 was completely dissolved. The solution was stored at roomtemperature.

[0246] A heat transfer medium-circulating 2-L stainless steel autoclaveequipped with a stirrer, a distillation column, a pressure regulator anda nitrogen line, wherein the heat transfer medium was set at 220° C.,was charged with 291 ml ethylene glycol, 432 g high-purity terephthalicacid and 1.1 ml triethylamine under stirring. Thereafter, the reactiontank was shut tightly by closing a cock of the distillation column andpressurized to 0.25 MPa in a nitrogen stream. The external temperatureof the distillation column was set at 140° C., while the temperature ofthe bottom of the reaction tank was set at 250° C., and the temperatureof the heat transfer medium was increased from 220° C. to 250° C. over30 minutes. Thereafter, the mixture was subjected to esterificationreaction at a heat transfer medium temperature of 250° C. at a pressureof 0.25 MPa with stirring at 60 r.p.m., during which water formed wasdistilled away from the system through the distillation column. A stageat which the internal temperature of the distillation column exceeded100° C. was regarded as an esterification reaction starting point, and101 minutes after that stage, a stage at which the internal temperatureof the distillation column came to be lower than 120° C. was regarded asa reaction terminating point. After the reaction was finished, thepressure in the reaction tank was gradually released and returned toatmospheric pressure. Subsequently, the above solution of aluminumacetylacetonate in ethylene glycol was added as a polycondensationcatalyst in an amount of 0.012 mol-% in terms of aluminum atom relativeto the acid component in the polyester and the above solution of Irganox1425 (Ciba Specialty Chemicals Inc.) in ethylene glycol in an amount of0.018 mol-% in terms of Irganox 1425 under stirring at 60 r.p.m.Thereafter, the mixture was stirred at a stirring rate of 60 r.p.m. for15 minutes at a heat transfer medium temperature of 250° C. in anitrogen atmosphere at normal pressure. Thereafter, the nitrogen linewas closed, and the temperature of the bottom of the reaction tank wasset at 275° C., and the temperature of the heat transfer medium wasincreased from 250° C. to 275° C. over 70 minutes during which thepressure in the reaction tank was gradually reduced with a vacuum pump.In this pressure reduction, the pressure was reduced from normalpressure to 40000 Pa for the first 20 minutes, then to 20000 Pa for 10minutes, then to 6650 Pa for 10 minutes, then to 2650 Pa for 10 minutes,and to 133 Pa for the last 20 minutes. During this step, the reactionmixture was stirred at 60 r.p.m. Ethylene glycol formed was distilledaway from the system through the distillation column. At a stage wherethe temperature of the heat transfer medium reached 275° C. and thedegree of vacuum in the tank reached 133 Pa, the vacuum line wascompletely opened. This stage was regarded as a polycondensationreaction initiating point. The degree of vacuum at this stage was 26.6Pa. Thereafter, the polycondensation reaction was carried out at a heattransfer medium temperature of 275° C. at a stirring rate of 60 r.p.m.while ethylene glycol formed was distilled away from the system throughthe distillation column. When the stirring torque reached apredetermined level, the stirring rate was gradually reduced from 60r.p.m. to 40 r.p.m. while the stirring torque was maintained. As thereaction proceeded, the degree of vacuum in the tank was graduallyincreased to 13.3 Pa or less finally at a polycondensation reactionterminating point. The polycondensation reaction was finished when 40r.p.m. was reached under predetermined stirring torque. The timerequired for the polycondensation reaction was 73 minutes. Thereafter,stirring was terminated, the vacuum line was closed, and while thetemperature of the heat transfer medium was kept at 275° C., nitrogenwas introduced gradually into the reaction tank so that the inside ofthe tank was returned to normal pressure. Thereafter, the melt polymerwas extruded in a strand form in cold water at a pressure of about 0.1MPa through discharge nozzles in a lower part of the reaction tank,rapidly cooled with the water and cut by a cutter into cylindrical resinchips having a length of about 3 mm and a diameter of about 2 mm. Theretention time in cold water was about 20 seconds. The IV of theresulting PET was 0.63 dl/g, the Tm was 256° C., the L value was 70.9,the a value was −2.9, and the b value was 4.4.

Example 30

[0247] To a mixture of bis(2-hydroxyethyl) terephthalate and oligomersproduced in a usual manner from high-purity terephthalic acid andethylene glycol in a 15-L stainless steel autoclave equipped with astirrer were added 2.5 g/l aluminum trisacetylacetonate solution as apolymerization catalyst in ethylene glycol in an amount of 0.014 mol-%in terms of aluminum atom relative to the acid component in thepolyester and 10 g/l Irganox 1425 (Ciba Specialty Chemicals Inc.) inethylene glycol in an amount of 0.01 mol-% in terms of Irganox 1425relative to the acid component in the polyester, and further 10 g/lcobalt acetate.4H₂O solution as a color tone improver in ethylene glycolin an amount of 3 ppm in terms of cobalt atom relative to the polymer tobe finally obtained, and the mixture was stirred at 245° C. for 10minutes in a nitrogen atmosphere at normal pressure. Then, thetemperature was increased to 275° C. over 50 minutes while the pressurein the reaction system was gradually reduced to 13.3 Pa (0.1 Torr), andthe polycondensation reaction was further conducted at 275° C. at 13.3Pa. The polycondensation time required for the IV of the polyethyleneterephthalate to reach about 0.65 dl/g was 80 minutes. The polyethyleneterephthalate having an intrinsic viscosity of about 0.65 dl/g obtainedby the polycondensation reaction was chipped in a usual manner. The PETresin chips was very excellent with a b value of 0.9.

Example 31

[0248] Polyester was polymerized in the same manner as in Example 30except that 2.5 g/l aluminum trisacetylacetonate solution as apolycondensation catalyst in ethylene glycol in an amount of 0.014 mol-%in terms of aluminum atom relative to the acid component in thepolyester, 10 g/l Irganox 1425 solution in ethylene glycol in an amountof 0.01 mol-% in terms of Irganox 1425 relative to the acid component inthe polyester, 50 g/l lithium acetate.2H₂O solution in ethylene glycolin an amount of 0.01 mol-% in terms of lithium atom relative to the acidcomponent, and Sandoplast blue 2B (Clariant) as a color tone improver inan amount of 1 ppm relative to the polymer to be finally obtained. Thepolycondensation time required for the IV of the polyethyleneterephthalate to reach about 0.65 dl/g was 70 minutes, and the resultingpolymer was excellent with a b value of −0.1.

Comparative Example 4

[0249] The same procedure as in Example 30 was repeated except thatantimony trioxide was used as a polycondensation catalyst in an amountof 0.05 mol-% in terms of antimony atom relative to the acid componentin PET. The polycondensation time required for the IV of thepolyethylene terephthalate to reach about 0.65 dl/g was 120 minutes, andthe b value of the resulting polymer was 2.6.

Example 32

[0250] A stainless steel autoclave equipped with a stirrer was chargedwith high-purity terephthalic acid and ethylene glycol in the molarratio of 1:2, and triethylamine was added in an amount of 0.3 mol-%relative to the acid component, and 23.5 wt-% titanium dioxide slurry inethylene glycol was added in an amount of 0.35 wt-% in terms of titaniumdioxide relative to the polyester to be finally obtained, and themixture was subjected to esterification reaction at a pressure of 0.25MPa at 250° C. while water was distilled away from the system, whereby aBHET mixture was obtained. To this BHET mixture were added 3 g/laluminum trisacetylacetonate solution in ethylene glycol in an amount of0.010 mol-% in terms of aluminum atom relative to the acid component inthe polyester, 100 g/l Irganox 1425 solution (Ciba Specialty ChemicalsInc.) in ethylene glycol in an amount of 0.015 mol-% in terms of Irganox1425 relative to the acid component in the polyester and HOSTALUX KS(Clariant) in an amount of 50 ppm relative to the polymer to be finallyobtained, and the mixture was stirred at 250° C. for 15 minutes in anitrogen atmosphere at normal pressure. Then, the temperature wasincreased to 280° C. over 60 minutes while the pressure in the reactionsystem was gradually reduced to 13.3 Pa (0.1 Torr), and thepolycondensation reaction was further conducted at 280° C. at 13.3 Pa.The polycondensation reaction was carried out for 80 minutes, wherebyPET having an IV of 0.67 dl/g was obtained. The AV of the resulting PETwas 6 equivalents/ton, the Tm was 255° C., the L value was 85.3, the avalue was 0.0, and the b value was 2.1.

Example 33

[0251] A stainless steel autoclave equipped with a stirrer was chargedwith high-purity terephthalic acid and ethylene glycol in the molarratio of 1:2, and triethylamine was added in an amount of 0.3 mol-%relative to the acid component, and esterification reaction was carriedout in the same manner as in Example 30, whereby a BHET mixture wasobtained. To this BHET mixture were added 3 g/l aluminumtrisacetylacetonate solution in ethylene glycol in an amount of 0.010mol-% in terms of aluminum atom relative to the acid component in thepolyester, 100 g/l Irganox 1425 solution (Ciba Specialty Chemicals Inc.)in ethylene glycol in an amount of 0.015 mol-% in terms of Irganox 1425relative to the acid component in the polyester and HOSTALUX KS(Clariant) in an amount of 250 ppm relative to the polymer to be finallyobtained, and polymerization of PET was carried out in the same manneras in Example 30. The polycondensation reaction was carried out for 95minutes, whereby PET having an IV of 0.66 dl/g was obtained. The AV ofthe resulting PET was not higher than 1 equivalent/ton, the Tm was 256°C., the L value was 71.1, the a value was −1.0, and the b value was 2.9.

Examples 34 to 39

[0252] To a mixture of bis(2-hydroxyethyl) terephthalate and oligomersproduced in a usual manner from high-purity terephthalic acid andethylene glycol were added 2.5 g/l aluminum trisacetylacetonate inethylene glycol in an amount of 0.014 mol-% relative to the acidcomponent in the polyester and 100 g/l Irganox 1425 in ethylene glycolin an amount of 0.01 mol-% in terms of Irganox 1425 relative to the acidcomponent, and further a color tone improver shown in Table 6 was added,and the mixture was stirred at 250° C. for 15 minutes in a nitrogenatmosphere at normal pressure. Then, the temperature was increased to280° C. over 40 minutes while the pressure in the reaction system wasgradually reduced to 133 Pa or less, and the polycondensation reactionwas further conducted at 280° C. at 13.3 Pa or less, whereby PET havingan IV of about 0.64 dl/g was polymerized. The amount of the color toneimprover added was 0.3 ppm relative to the polymer to be finallyobtained. The color tone improver was added as slurry at a concentrationof 1 g/kg in ethylene glycol. The examination results of the color toneof the resulting PET are shown in Table 6. The color tone improvers usedin Examples 37 to 39 are those containing a dispersant.

Example 40 Spinning Example 1 of Polyester

[0253] A stainless steel autoclave equipped with a stirrer was chargedwith high-purity terephthalic acid and ethylene glycol in the molarratio of 1:2, and triethylamine was added in an amount of 0.3 mol-%relative to the acid component, and 23.5 wt-% titanium dioxide slurry inethylene glycol was added in an amount of 0.35 wt-% in terms of titaniumdioxide relative to the polyester, and the mixture was subjected toesterification reaction at a pressure of 0.25 MPa at 260° C. while waterwas distilled away from the system, whereby a BHET mixture was obtained.To this BHET mixture were added 2.5 g/l aluminum trisacetylacetonate asa polycondensation catalyst in ethylene glycol in an amount of 0.01mol-% in terms of aluminum atom relative to the acid component in thepolyester and 100 g/l Irganox 1425 solution in ethylene glycol in anamount of 0.015 mol-% in terms of Irganox 1425 relative to the acidcomponent, and the mixture was stirred at 250° C. for 15 minutes in anitrogen atmosphere at normal pressure. Then, the temperature wasincreased to 280° C. over 70 minutes while the pressure in the reactionsystem was gradually reduced to 266 Pa (2 Torr), and thepolycondensation reaction was further conducted at 280° C. at 266 Pa.The polycondensation reaction was carried out for 60 minutes, and theresulting PET was chipped in a usual manner. The IV of the resulting PETwas 0.61 dl/g, the AV was 11 equivalents/ton, the L value was 83.8, thea value was −2.2, and the b value was 8.5.

[0254] The resultant PET resin chips were dried, fed to a melt extruder,discharged at 275° C. through a spinneret having 24 orifices with a borediameter of 0.14 mmφ, cooled in a usual manner, subjected to oiling anddrawn at a rate of 1000 m/min. The rate of discharge was 17 g/min.Subsequently, 3 strands were combined, stretched 3.58-fold at apreheating roller temperature of 80° C. and at a setting temperature of150° C. to give a drawn polyester yarn of 142 decitex with 72 filaments.The operativeness in spinning and drawing was very good, and thephysical characteristics of the resultant yarn were not problematic foruse in clothing. Physical properties of the drawn yarn are shown inTable 7.

[0255] The resulting yarn was interweaved with a machine at mesh densityof 4.5 at Feed 6. Further, it was refined, dried and preset. Afterrefining, L* was 93.5, a* was −0.9, b* was 3.0, and the sample showedhigher yellow discoloration than that produced with the antimonycatalyst in the Comparative Examples, but a visible differencetherebetween could be hardly recognized. The degree of absorption ofdyes and light-fastness were almost similar to those of the product withthe antimony catalyst.

Example 41 Spinning Example 2 of Polyester

[0256] PET was polymerized in the same manner as in Example 40 exceptthat 20 g/l cobalt (II) acetate.4H₂O solution in ethylene glycol wasadded as a color tone improver in an amount of 3 ppm in terms of cobaltatom relative to the polyester. The time necessary for thepolycondensation reaction was 60 minutes. The IV of the resulting PETresin chips was 0.61 dl/g, the AV was 11 equivalents/ton, the L valuewas 82.2, the a value was −1.9, and the b value was 6.4.

[0257] The resultant PET resin chips were dried, spun and drawn in thesame manner as in Example 40. However, the rate of discharge was 20g/min. The strands were stretched 3.44-fold to give an orientedpolyester yarn of 174 decitex with 72 filaments. The operativeness inspinning and drawing was very good, and the physical characteristics ofthe resultant yarn were not problematic for use in clothing. Thephysical properties etc. of the drawn yarn are shown in Table 7.

[0258] The resulting yarn was interweaved with a machine, refined, driedand preset in the same manner as in Example 40. After refining, L* was92.9, a* was −0.7, b* was 2.7, and the sample indicated almost the samemeasurement result as that of the product with the antimony catalyst inthe Comparative Examples, and a visible difference therebetween could behardly recognized. The degree of absorption of dyes and light-fastnesswere almost similar to those of the product with the antimony catalyst.

Comparative Example 5 Spinning Comparative Example of Polyester

[0259] PET was polymerized in the same manner as in Example 40 exceptthat antimony trioxide was added as a polycondensation catalyst in anamount of 0.04 mol-% in terms of antimony atom relative to the acidcomponent in the polyester. The time necessary for the polycondensationreaction was 74 minutes. The IV of the resulting PET resin chips was0.63 dl/g, the AV was 6 equivalents/ton, the L value was 81.0, the avalue was −1.9, and the b value was 6.2.

[0260] The resultant PET resin chips were dried, spun and drawn in thesame manner as in Example 40. However, the rate of discharge was 19g/min. The strands were stretched 3.42-fold to give a polyester drawnyarn of 174 decitex with 72 filaments. The physical properties etc. ofthe drawn yarn are shown in Table 7. The resulting yarns wereinterweaved with a machine, refined, dried and preset in the same manneras in Example 40. After refining, L* was 92.2, a* as −0.6, and b* was2.4.

Example 42 Spinning Example 3 of Polyester

[0261] A polymerization device equipped with a stirrer, a distillationcolumn and a pressure regulator was charged with 164 parts ofhigh-purity terephthalic acid and 115 parts of ethylene glycol, and aphosphorus compound represented by the chemical formula below (chemicalformula 3) was added such that phosphorus atoms were contained at alevel of 6000 ppm in the polyester to be finally obtained. Then, 0.7part of triethylamine was added, and titanium dioxide was added so as tobe contained in an amount of 0.35 wt-% relative to the polyester to befinally obtained, and the mixture was subjected to esterificationreaction at a pressure of 0.25 MPa at 240° C. while water formed wassuccessively removed. After esterification, 2.5 g/l aluminumacetylacetonate in ethylene glycol was added as a catalyst in an amountof 0.011 mol-% in terms of aluminum atom relative to the acid componentin the polyester and 100 g/l Irganox 1425 solution in ethylene glycol inan amount of 0.01 mol-% in terms of Irganox 1425 relative to the acidcomponent in the polyester, and the mixture was stirred at 240° C. for20 minutes in a nitrogen atmosphere at normal pressure. Then, thetemperature was increased to 280° C. over 75 minutes while the pressurein the reaction system was gradually reduced to 665 Pa or less, and thepolycondensation reaction was further conducted at 280° C. at 665 Pa orless. The polyethylene terephthalate having an intrinsic viscosity of0.60 dl/g obtained by the polycondensation reaction was chipped in ausual manner. The resin chips had an AV of 13 equivalents/ton and a Tmof 245° C. (formula 3)

[0262] The PET resin chips were dried, fed to a melt extruder,discharged at 261° C. through a spinneret having 108 orifices with abore diameter of 0.14 mmφ, cooled, solidified, drawn at a spinning rateof 2400 m/min., and without rolling, drawn 1.625-fold between apreheating roller heated at 80° C. and a setting roller heated at 150°C. to give a completed polyester yarn of about 96 decitex with 216filaments. In spinning, the number of times strands were cut every 8nozzles was less than 1.0 per day, and no insoluble particle wasrecognized around the orifices for 4 days. The operativeness of spinningwas significantly superior as compared with spinning of copolymerizedpolyethylene terephthalate produced with the antimony catalyst. Further,the physical characteristics etc. of the resultant yarn were notproblematic for use in clothing.

Example 43 Spinning Example 4 of Polyester

[0263] A stainless steel autoclave equipped with a stirrer was chargedwith high-purity terephthalic acid (acid component accounting for 99mol-% of the total acid component), 5-sodium sulfoisophthalic acidethylene glycol ester (acid component accounting for 1 mol-%) andethylene glycol (200 mol-% relative to the acid component), and sodiumacetate was added in an amount of 0.2 mol-% in terms of sodium atomrelative to the acid component in the polyester, triethylamine in anamount of 0.1 mol-% relative to the acid component in the polyester andtitanium dioxide in an amount of 0.35 wt-% relative to the polyester tobe finally obtained, and the mixture was subjected to esterificationreaction for 2 hours at a pressure of 0.25 MPa at 260° C. while waterformed was successively removed. After esterification, 4.5 mol-%neopentyl glycol-ethylene oxide adduct (2 mol-% relative to the glycolcomponent in the polyester) was added, and 13 g/l aluminum chloride inethylene glycol was added as a polycondensation catalyst in an amount of20 ppm in terms of aluminum atom relative to the finally obtainedpolyester and 5 g/l Irganox 1222 solution in ethylene glycol in anamount of 0.04 mol-% in terms of Irganox 1222 relative to the acidcomponent in the polyester, and the mixture was stirred at 250° C. for15 minutes in a nitrogen atmosphere at normal pressure. Then, thetemperature was increased to 275° C. over 80 minutes while the pressurein the reaction system was gradually reduced to 39.9 Pa (0.3 Torr), andthe polycondensation reaction was further conducted at 275° C. at 39.9Pa. The polyethylene terephthalate having an intrinsic viscosity of 0.60dl/g obtained by the polycondensation reaction for 52 minutes waschipped in a usual manner. The resin chips had an AV of 9equivalents/ton and a Tm of 245° C.

[0264] The resultant PET resin chips were dried, fed to a melt extruder,discharged at 270° C. through a spinneret, cooled in a usual manner,subjected to oiling and drawn at a rate of 1500 m/min. Subsequently, thestrands were drawn 2.3-fold on a preheating roller at 80° C. and at asetting temperature of 150° C. to give a polyester yarn. Theoperativeness in spinning and drawing was very good, and the physicalcharacteristics etc. of the resultant yarn were not problematic for usein clothing.

Example 44 Example 1 of Bottle

[0265] A polymerization device equipped with a stirrer, a distillationcolumn and a pressure regulator was charged with high-purityterephthalic acid (acid component accounting for 98.4 mol-% of the totalacid component), isophthalic acid (acid component accounting for 1.6mol-%) and ethylene glycol (200 mol-% relative to the acid component),and triethylamine was added in an amount of 0.3 mol-% relative to theacid component, and the mixture was subjected to esterification reactionat a pressure of 0.25 MPa at 245° C. while water was successivelyremoved, whereby a BHET mixture having a degree of esterification of 95%or more was obtained. To this BHET mixture was added 100 g/l Irganox1425 solution in ethylene glycol in an amount of 0.025 mol-% in terms ofIrganox 1425 relative to the acid component in the polyester, and 20 g/lcobalt (II) acetate.4H₂O solution in ethylene glycol was added in anamount of 5 ppm in terms of cobalt atom relative to the polyester, andthe mixture was stirred at 245° C. for 10 minutes in a nitrogenatmosphere at normal pressure. Then, 3 g/l aluminum trisacetylacetonatesolution in ethylene glycol was added in an amount of 0.014 mol-% interms of aluminum atom relative to the acid component in the polyester,and the mixture was stirred at 245° C. for 10 minutes in a nitrogenatmosphere at normal pressure. Then, the temperature was increased to275° C. over 75 minutes while the pressure in the reaction system wasgradually reduced to 133 Pa or less, and the polycondensation reactionwas further conducted at 275° C. at 133 Pa or less. After thepolycondensation reaction for about 80 minutes, the polyethyleneterephthalate was chipped in a usual manner. The resulting polyesterresin chips had an intrinsic viscosity of 0.63 dl/g, an AV of 3equivalents/ton and a Tm of 252° C.

[0266] The resin chips were subjected to precrystallization at 160° C.and solid state polymerization, to give resin chips having an IV of 0.78dl/g.

[0267] Then, the resin chips were dried in an oven using dry nitrogenand molded into a preform by an injection molding machine M-150C (DM)(Meiki Seisakusho) at a cylinder temperature of 280° C. and at a moldtemperature of 25° C. This preform was heated again to 100° C. andsubjected to biaxial blow molding at a blow pressure of 30 kg/cm² in amold at 30° C. in a blow molding machine LB-01E (Corpoplast Co., Ltd.),to give a 1500 cc hollow molded article. The L value of the resultinghollow molded article was 89.3, the a value was 0.1, and the b value was1.0, and the molded article was visually excellent to the same degree asthat of the product by the antimony catalyst in the ComparativeExamples. The resulting hollow molded article was also excellent intransparency.

Example 45 Example 2 of Bottle

[0268] A polymerization device equipped with a stirrer, a distillationcolumn and a pressure regulator was charged with high-purityterephthalic acid (acid component accounting for 98.4 mol-% of the totalacid component), isophthalic acid (acid component accounting for 1.6mol-%) and ethylene glycol (200 mol-% relative to the acid component),and triethylamine was added in an amount of 0.3 mol-% relative to theacid component, and 8 g/l Irganox 1222 solution in ethylene glycol in anamount of 0.03 mol-% in terms of Irganox 1222 relative to the acidcomponent in the polyester, and the mixture was subjected toesterification reaction at a pressure of 0.25 MPa at 245° C. while waterwas successively removed, whereby a BHET mixture having a degree ofesterification of 95% or more was obtained. To this BHET mixture wereadded 3 g/l aluminum trisacetylacetonate in ethylene glycol in an amountof 0.014 mol-% in terms of aluminum atom relative to the acid componentin the polyester, 100 g/l magnesium acetate.4H₂O in ethylene glycol inan amount of 0.01 mol-% in terms of magnesium atom relative to the acidcomponent and 20 g/l cobalt (II) acetate.4H₂O in ethylene glycol in anamount of 5 ppm in terms of cobalt atom relative to the polyester, andthe mixture was stirred at 245° C. for 10 minutes in a nitrogenatmosphere at normal pressure. Then, the temperature was increased to275° C. over 75 minutes while the pressure in the reaction system wasgradually reduced to 133 Pa or less, and the polycondensation reactionwas further conducted at 275° C. at 133 Pa or less. After thepolycondensation reaction for about 100 minutes, the polyester waschipped in a usual manner. The resulting polyester resin chips had an IVof 0.63 dl/g, an AV of 6 equivalents/ton and a Tm of 251° C.

[0269] The resin chips were subjected to precrystallization and solidstate polymerization in the same manner as in Example 44, to give resinchips having an IV of 0.81 dl/g. The resin chips were used to form ahollow molded article in the same manner as in Example 44. The L valueof the resulting hollow molded article was 89.4, the a value was 0.2,and the b value was 1.2, and the molded article was visually excellentto the same degree as that of the product by the antimony catalyst inthe Comparative Examples. The resulting hollow molded article was alsoexcellent in transparency.

Example 46 Example 3 of Bottle

[0270] 20 g/l aqueous basic aluminum acetate solution (hydroxy aluminumdiacetate, manufactured by ALDRICH) was prepared at about 70° C.Ethylene glycol was added to this aqueous solution in the ratio of 2:1(ratio by volume) to give a catalyst solution.

[0271] Polyester was polymerized in the same manner as in Example 44except that in place of aluminum trisacetylacetonate, the above basicaluminum acetate solution was added as a polycondensation catalyst in anamount of 0.014 mol-% in terms of aluminum atom relative to the acidcomponent in the polyester. The polycondensation reaction was carriedout for about 90 minutes. The resulting polyester resin chips had an IVof 0.63 dl/g, an AV of 6 equivalents/ton, and a Tm of 252° C.

[0272] The resin chips were subjected to precrystallization and solidstate polymerization in the same manner as in Example 44, to give resinchips having an IV of 0.79 dl/g. The resin chips were used to form ahollow molded article in the same manner as in Example 44. The L valueof the resulting hollow molded article was 89.5, the a value was 0.1,and the b value was 1.0, and the molded article was visually excellentto the same degree as that of the product by the antimony catalyst inthe Comparative Examples. The resulting hollow molded article was alsoexcellent in transparency.

Comparative Example 6 Comparative Example 1 of Bottle

[0273] Polyester was polymerized in the same manner as in Example B1except that antimony trioxide was added as a polycondensation catalystin an amount of 200 ppm in terms of antimony atom relative to theresulting polyester, and cobalt (II) acetate.4H₂O was added as anadditive in an amount of 10 ppm in terms of cobalt atom relative to thepolyester and phosphoric acid as an additive in an amount of 30 ppm interms of phosphorus atom relative to the polyester. The polycondensationreaction was carried out for about 80 minutes. The resulting polyesterresin chips had an IV of 0.65 dl/g, an AV of 2 equivalents/ton, and a Tmof 252° C.

[0274] The resin chips were subjected to precrystallization and solidstate polymerization in the same manner as in Example 44, to give resinchips having an IV of 0.79 dl/g. The resin chips were used to form ahollow molded article in the same manner as in Example B1. The L valueof the resulting hollow molded article was 88.3, the a value was 0.5,and the b value was 1.1.

Example 47 Example 1 of Resin Plate

[0275] High-purity terephthalic acid (acid component accounting for 98.4mol-% of the total acid component), isophthalic acid (acid componentaccounting for 1.6 mol-%) and ethylene glycol (200 mol-% based on theacid component) were charged, and triethylamine was added in an amountof 0.3 mol-% relative to the acid component, and the mixture wassubjected to esterification reaction at a pressure of 0.25 MPa at 245°C. while water was distilled away from the system, whereby a BHETmixture having a degree of esterification of 95% or more was obtained.To this BHET mixture were added 3 g/l aluminum trisacetylacetonatesolution as a polycondensation catalyst in ethylene glycol in an amountof 0.008 mol-% in terms of aluminum atom relative to the acid componentin the polyester and 100 g/l Irganox 1425 (Ciba Specialty ChemicalsInc.) in ethylene glycol in an amount of 0.012 mol-% in terms of Irganox1425 relative to the acid component in the polyester, and further 100g/l magnesium acetate.4H₂O in ethylene glycol was added in an amount of0.01 mol-% in terms of magnesium atom relative to the acid component,and the mixture was stirred at 245° C. for 10 minutes in a nitrogenatmosphere at normal pressure. Then, the temperature was increased to285° C. over 75 minutes while the pressure in the reaction system wasgradually reduced to 133 Pa or less, and the polycondensation reactionwas further conducted at 285° C. at 133 Pa or less, whereby polyesterresin chips having an IV of 0.64 dl/g were obtained.

[0276] The resin chips were preliminarily crystallized at 160° C. andthen subjected to solid state polymerization at 200° C., to give resinchips having an IV of 0.80 dl/g.

[0277] The resin chips were dried and then molded into a stepped platemolded article by an injection molding machine M-150C (DM) (manufacturedby Meiki Seisakusho) with a cylinder temperature of 290° C. Theresultant stepped molded plate had about 3 cm×about 5 cm stepped platesof 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11 mm in thickness, each weighingabout 146 g. The plate of 4 mm in thickness was used in measurement ofhaze (haze %). The resultant stepped plate molded article had a haze of2% and an aldehyde content of 18 ppm, both of which were excellent.

Example 48 Example 2 of Resin Plate

[0278] A stepped plate molded article was obtained in the same manner asin Example 47 except that 3 g/l aluminum trisacetylacetonate solution inethylene glycol was added as a polycondensation catalyst in an amount of0.008 mol-% in terms of aluminum atom relative to the acid component inthe polyester, 100 g/l Irganox 1425 (Ciba Specialty Chemicals Inc.) inethylene glycol was added in an amount of 0.012 mol-% in terms ofIrganox 1425 relative to the acid component in the polyester, andfurther 50 g/l sodium acetate in ethylene glycol was added in an amountof 0.01 mol-% in terms of sodium atom relative to the acid component.The haze of the resultant stepped plate molded article was as relativelyhigh as 8%, but the content of aldehyde was very good (16 ppm).

Example 49 Example 3 of Resin Plate

[0279] A stepped plate molded article was obtained in the same manner asin Example 47 except that 3 g/l aluminum trisacetylacetonate solution inethylene glycol was added as a polycondensation catalyst in an amount of0.008 mol-% in terms of aluminum atom relative to the acid component inthe polyester, 100 g/l Irganox 1425 (Ciba Specialty Chemicals Inc.) inethylene glycol was added in an amount of 0.02 mol-% in terms of Irganox1425 relative to the acid component in the polyester, and further 50 g/lsodium acetate in ethylene glycol was added in an amount of 0.01 mol-%in terms of sodium atom relative to the acid component. The haze of theresultant stepped plate molded article was 2%, and the content ofaldehyde was 19 ppm, both of which were excellent.

Example 50 Example 1 of Film

[0280] A polymerization device equipped with a stirrer, a distillationcolumn and a pressure regulator was charged with high-purityterephthalic acid and ethylene glycol in the molar ratio of 1:2, andtriethylamine was added in an amount of 0.3 mol-% relative to the acidcomponent, and the mixture was subjected to esterification reaction at apressure of 0.25 MPa at 240° C. while water formed was successivelyremoved. After esterification, 2.5 g/l aluminum acetylacetonate inethylene glycol was added as a catalyst in an amount of 0.011 mol-% interms of aluminum atom relative to the acid component in the polyesterand 100 g/l Irganox 1425 (Ciba Specialty Chemicals Inc.) in ethyleneglycol in an amount of 0.01 mol-% in terms of Irganox 1425 relative tothe acid component in the polyester, and the mixture was stirred at 240°C. for 20 minutes in a nitrogen atmosphere at normal pressure. Then, thetemperature was increased to 280° C. over 75 minutes while the pressurein the reaction system was gradually reduced to 665 Pa or less, and thepolycondensation reaction was further conducted at 280° C. at 665 Pa orless. The polyethylene terephthalate having an intrinsic viscosity of0.66 dl/g obtained by the polycondensation reaction was chipped in ausual manner. The resin chips had an AV of 11 equivalents/ton and a Tmof 256° C.

[0281] The PET resin chips thus obtained were vacuum-dried at 120° C.for 24 hours. The PET resin chips were quantitatively fed to an extruderand melt-extruded into a sheet at about 280° C., quenched and solidifiedon a metal roll kept at a surface temperature of about 20° C., to give acast film of 860 μm in thickness.

[0282] Then, this cast film was heated to about 95° C. with a series ofheated rollers and an infrared heater and then drawn 3.4-fold in thelonger direction with a series of rollers different in circumferentialvelocity to give a monoaxial oriented PET film. Subsequently, the filmwas drawn 3.8-fold in the width direction by a tender at about 120° C.,and while the width length of the film was fixed, the film was heated at225° C. for 4 seconds, followed by relaxation by 5% at 200° C. for about4 seconds, to give a biaxial oriented PET film of 70 μm in thickness.The resulting film was cut into strips in the lengthwise direction andcross direction respectively and measured for strength and elongation.The strength was 23.6 kg/mm² in the lengthwise direction and 26.9 kg/mm²in the cross direction, and the elongation was 162% in the lengthwisedirection and 109% in the cross direction, which were almost similar tothose of a film prepared in the same manner by using the antimonycatalyst. In respect of transparency, refractive index and thermalshrinkage, the resulting film was almost comparative to a film preparedin the same manner by using the antimony catalyst.

Example 51 Example 2 of Film

[0283] A film was prepared in the same manner as in Example 50 exceptthat when the PET resin chips polymerized in Example 50 were used toform a film, PET resin chips polymerized with cobalt acetate as acatalyst were simultaneously fed to the extruder. The resin chips weremixed in such a ratio that 1.5 ppm cobalt atom was contained in thepolyester film to be finally obtained. The resulting film was excellentin color tone with yellow discoloration reduced.

Example 52 Example 3 of Film

[0284] A polymerization device equipped with a stirrer, a distillationcolumn and a pressure regulator was charged with 86.5 kg high-purityterephthalic acid and ethylene glycol in the molar ratio of 1:2, 52.96 gmagnesium acetate and 3.57 g sodium acetate, and triethylamine was addedin an amount of 0.3 mol-% relative to the acid component, and themixture was subjected to esterification reaction for 130 minutes at apressure of 0.20 MPa at 240° C. while water was successively removed,whereby a BHET mixture having a degree of esterification of 95% or morewas obtained. To this BHET mixture was added 50 g/l triethylphosphonoacetate in ethylene glycol in an amount of 0.0095 mol-% interms of triethyl phosphonoacetate relative to the acid component, andthe mixture was stirred at 240° C. for 10 minutes in a nitrogenatmosphere at normal pressure. Then, 100 g/l Irganox 1425 in ethyleneglycol was added in an amount of 0.012 mol-% in terms of Irganox 1425relative to the acid component, and 2.5 g/l aluminum acetylacetonate inethylene glycol was added in an amount of 0.008 mol-% in terms ofaluminum atom relative to the acid component in the polyester, and themixture was stirred at 240° C. for 10 minutes in a nitrogen atmosphereat normal pressure. Then, the temperature was increased to 275° C. over75 minutes while the pressure in the reaction system was graduallyreduced to 13.3 Pa (0.1 Torr), and the polycondensation reaction wasfurther conducted at 275° C. at 13.3 Pa. The melt polymer was extrudedthrough discharge nozzles into water and cut by a cutter intocylindrical chips having a diameter of about 3 mm and a length of about5 mm. The intrinsic viscosity of the resulting polymer was 0.61 dl/g,and the polymerization time necessary for obtaining this intrinsicviscosity was 108 minutes, and the AV was 15 equivalents/ton, the Tc1was 161° C., the Tm was 256° C., the Tc2 was 180° C., the L value was63.5, the a value was −2.4, the b value was 4.7, the ρi was 0.162×10⁸Ω·cm, and the TS was 0.24. The PET is excellent in polymer physicalproperties and ρi, and in film making, the resin can be used to producea stable film.

Example 53 Example 4 of Film

[0285] A polymerization device equipped with a stirrer, a distillationcolumn and a pressure regulator was charged with 86.5 kg high-purityterephthalic acid and ethylene glycol in the molar ratio of 1:2, 52.96 gmagnesium acetate, 3.57 g sodium acetate and Irganox 1222 in an amountof 0.02 mol-% in terms of Irganox 1222 relative to the acid component,and triethylamine was added in an amount of 0.3 mol-% relative to theacid component, and the mixture was subjected to esterification reactionfor 130 minutes at a pressure of 0.20 MPa at 240° C. while water wassuccessively removed, whereby a BHET mixture having a degree ofesterification of 95% or more was obtained. To this BHET mixture wereadded 50 g/l triethyl phosphonoacetate in ethylene glycol in an amountof 0.0095 mol-% in terms of triethyl phosphonoacetate relative to theacid component, and the mixture was stirred at 240° C. for 10 minutes ina nitrogen atmosphere at normal pressure. Thereafter, 2.5 g/l aluminumacetylacetonate in ethylene glycol was added in an amount of 0.01 mol-%in terms of aluminum atom relative to the acid component in thepolyester, and the mixture was stirred at 240° C. for 10 minutes in anitrogen atmosphere at normal pressure. Then, the temperature wasincreased to 275° C. over 100 minutes while the pressure in the reactionsystem was gradually reduced to 13.3 Pa (0.1 Torr), and thepolycondensation reaction was further conducted at 275° C. at 13.3 Pa.The melt polymer was extruded through discharge nozzles into water andcut by a cutter into cylindrical chips having a diameter of about 3 mmand a length of about 5 mm. The intrinsic viscosity of the resultingpolymer was 0.61 dl/g, and the polymerization time necessary forobtaining this intrinsic viscosity was 95 minutes, and the AV was 12.6equivalents/ton, the Tc1 was 160° C., the Tm was 256° C., the Tc2 was183° C., the L value was 63.3, the a value was −2.7, the b value was5.6, the ρi was 0.178×10⁸ Ω·cm, and the Ts was 0.25. The PET isexcellent in polymer physical properties and ρi, and in film making, theresin can be used to produce a stable film.

Example 54 Example 5 of Film

[0286] A electrical-wire heating 2-L stainless steel autoclave equippedwith a stirrer was charged with high-purity terephthalic acid andethylene glycol in the molar ratio of 1:2.2, and 50 g/l magnesiumacetate in ethylene glycol was added in an amount of 0.047 mol-% interms of magnesium atom relative to the acid component, 20 g/l sodiumacetate in ethylene glycol in an amount of 0.0084 mol-% in terms ofsodium atom relative to the acid component, 5 g/l Irganox 1222 inethylene glycol in an amount of 0.035 mol-% in terms of Irganox 1222relative to the acid component, and silica synthesized as inertparticles by a wet process (average particle diameter determined by alaser method: 2.7 μm) in an amount of 0.207 weight-% relative to theweight of the polymer to be obtained, and the mixture was subjected toesterification reaction for 125 minutes at a pressure of 0.25 MPa at250° C. while water was successively distilled away from the system,whereby a BHET mixture having a degree of esterification of 95% or morewas obtained. After this BHET mixture was heated to 260° C. over 30minutes, and 2.5 g/l aluminum acetylacetonate in ethylene glycol wasadded as a polycondensation catalyst in an amount of 0.01 mol-% in termsof aluminum atom relative to the acid component in the polyester, andthe mixture was stirred at 260° C. for 10 minutes in a nitrogenatmosphere at normal pressure. Then, the temperature was increased to285° C. over 30 minutes while the pressure in the reaction system wasgradually reduced to 13.3 Pa (0.1 Torr), and the polycondensationreaction was further conducted at 285° C. at 13.3 Pa. The melt polymerwas extruded through discharge nozzles into water and cut by a cutterinto cylindrical chips having a diameter of about 3 mm and a length ofabout 5 mm. The intrinsic viscosity of the resulting polymer was 0.60dl/g, and the polymerization time necessary for obtaining this intrinsicviscosity was 56 minutes, and the AV was 19.5 equivalents/ton, the Lvalue was 64.5, the a value was −3.0, the b value was 5.9, and the ρiwas 0.199×10⁸ Ω·cm. The PET is excellent in polymer physical propertiesand ρi, and in film making, the resin can be used to produce a stablefilm.

Example 55

[0287] A stainless steel autoclave was charged with high-purityterephthalic acid, ethylene glycol in a molar ratio of 1.7 to the acidcomponent, and 1,4-cyclohexane dimethanol in a molar ratio of 0.32 tothe acid component, and the mixture was subjected to esterificationreaction for 180 minutes at a pressure of 0.25 MPa at 240° C. whilewater formed was successively distilled away from the system, whereby anoligomer was obtained. To the oligomer were added aluminumtrisacetylacetonate solution in an amount of 120 ppm relative to thepolymer to be finally obtained and Irganox 1425 in an amount of 190 ppmrelative to the polymer to be finally obtained, and the mixture wasstirred in a nitrogen atmosphere at normal pressure, and then thetemperature was increased to 280° C. over 75 minutes while the pressurein the reaction system was gradually reduced to about 160 Pa, and thepolycondensation reaction was further conducted for about 60 minutes at280° C. at about 160 Pa, to give PET copolymerized with 1,4-hexanedimethanol. The IV of the resulting polymer was 0.68 dl/g, the L valuewas 62.4, and the b value was 3.2.

Effect of the Invention

[0288] According to this invention, there is provided a novel polyesterpolymerization catalyst based on a component other than antimony orgermanium compounds, which has excellent catalytic activity and givespolyester excellent in thermal stability, stability to thermaloxidation, and hydrolytic stability, as well as polyester produced byusing the same and a process for producing polyester.

Industrial Applicability

[0289] The polyester of this invention can be applied for example tofibers for clothing, interior and bedding fibers in curtains, carpetsand futon cotton, fibers for industrial materials such as tire cords andropes, various fabrics, knitting, nonwoven fabrics of short or longfibers, films such as packaging films, industrial films, optical films,films for magnetic tapes, photographic films, films for can laminates,films for capacitors, thermally shrinkable films, gas barrier films,white films and easily cut films, hollow molded articles such asthermally unstable bottles, thermally stable bottles, direct blownbottles, gas barrier bottles, pressure-resistant bottles and heat- andpressure-resistant bottles, sheets such as A-PET and C-PET, and variousmolded articles of engineering plastics such as glass fiber-reinforcedpolyester and elastomer, and coatings and adhesives. TABLE 1 Physicalproperties of polyester Polymeri- IV AV Catalyst zation before (equiva-Amount time test lent/ L a b Tm Tc1 Tc2 DEG Haze Component (mol-%) (min)(dlg⁻¹) ton) value value value (° C.) (° C.) (° C.) (mol %) (%) TS TOSHS Example Aluminum 0.015 0.01 1 chloride or Irganox 0.02 75 0.65 1.468.47 −2.73 5.32 258 141 186 2.1 0.1 0.17 less 0.05 1425 ExampleAluminum 0.015 2 chloride Irganox 0.01 1222 Lithium 0.025 65 0.65 0.168.21 −2.12 4.48 259 142 196 — — 0.19 0.07 0.09 acetate · 2H₂O ExampleAluminum 0.015 3 chloride Irganox 0.01 1425 Lithium 0.01 66 0.65 4.169.3 −2.77 5.41 259 141 184 2.1 0.1 0.21 0.01 0.07 acetate · 2H₂OCompar- Aluminum 0.015 tc 180 — — — — — — — — — — — — — ative chlorideor Example more 1 Compar- Antimony 0.05 65 0.65 4.4 55.03 − 0.29 1.06257 131 209 2.2 0.5 0.22 0.01 0.05 ative trioxide or Example less 1

[0290] TABLE 2 Physical properties of polyster Catalyst AV AmountPolymerization IV (equivalent · L a b Tm Tc1 Tc2 Component (mol-%) time(min) (dlg⁻¹) ton) value value value (° C.) (° C.) (° C.) Example 4Aluminum trisacetylacetonate 0.014 Irganox 1425 0.01 123 0.61 4 67.7−1.9 3.4 256 145 184 Example 5 Polyaluminum chloride 0.014 Irganox 14250.01 119 0.61 1 67.7 −2.2 3.8 257 146 186 Example 6 Basic aluminumchloride 0.014 Irganox 1425 0.01 125 0.60 <1 66.9 −1.8 3.3 257 145 182Example 7 Aluminum chloride · 6H₂O 0.014 Irganox 1425 0.01 121 0.60 <166.8 −1.9 3.4 256 147 181 Example 8 Polyaluminum chloride 0.014 Irganox1222 0.03 Magnesium acetate · 4H₂O 0.01 123 0.60 1 66.2 −1.3 2.1 256 145186 Comparative Antimony trioxide 0.04 112 0.61 <1 62.0 −0.8 2.2 256 131209 Example 3

[0291] TABLE 3 Physical properties of polyster Catalyst AV AmountPolymerization IV (equivalent · L a b Tm Tc1 Tc2 Component (mol-%) time(min) (dlg⁻¹) ton) value value value (° C.) (° C.) (° C.) Example 9Basic aluminum acetate 0.014 Irganox 1425 0.01 132 0.61 <1 64.9 −1.7 3.7256 147 182 Example 10 Basic aluminum acetate 0.014 Irganox 1425 0.01133 0.60 <1 66.6 −2.2 4.0 256 143 184 Example 11 Aluminum lactate 0.014Irganox 1425 0.01 124 0.60   3 66.5 −2.1 4.4 256 148 185

[0292] TABLE 4 Aluminum compound Phosphorus compound AV₀ Amount AmountCharging (molar fraction) IV equivalent/ OHV Es (mol-%) Form (mol-%)Form EG/TPA dl/g ton o Pn (%) Example 17 0.008 Solution 0.012 Solution2.0 0.06 362 4816 1.7 95.9 Example 18 0.008 Solution 0.012 Solution 2.00.06 505 4517 1.8 94.4 Example 19 0.008 Solution 0.012 Solution 2.0 0.06939 4796 1.6 89.5 Example 20 0.008 Solution 0.012 Solution 1.5 0.07 6773492 2.2 92.7 Example 21 0.006 Solution 0.01 Solution 2.0 0.06 510 46891.7 94.3 Example 22 0.014 Solution 0.03 Solution 2.0 0.06 510 4689 1.794.3 Example 23 0.014 solution 0.03 Solution 2.0 ≦0.01 — — — — Example24 0.008 slurry 0.012 Solution 2.0 0.06 545 4508 1.8 93.9 Example 250.008 powder 0.012 Powder 2.0 0.06 495 5012 1.6 94.4

[0293] TABLE 5 Polycondensation time IV DEG (min) (dl/g) (mol %) L valuea value b value Example 17 120 0.637 2.28 67.95 −2.44 3.75 Example 18108 0.629 2.12 69.72 −1.96 2.87 Example 19 117 0.626 1.87 69.33 −2.002.65 Example 20 134 0.633 2.07 70.23 −2.07 3.44 Example 21 130 0.6082.34 69.53 −1.59 2.55 Example 22 180 0.410 2.19 — — — Example 23 1600.600 2.43 64.52 −1.32 1.82 Example 24 117 0.630 2.29 69.54 −2.01 2.68Example 25 120 0.628 2.35 69.8 −2.05 2.88

[0294] TABLE 6 Presence or absence of L a b Example Color tone improvera dispersant value value value 34 phthalocyanine blue absent 68.6 −4.52.8 35 ultramarine Absent 69.4 −2.6 4.2 36 anthraquinone- Absent 69.0−1.7 2.3 based dye 37 ultramarine Present 70.2 −2.0 3.8 38phthalocyanine- Present 69.3 −4.6 2.5 based pigment 39 anthraquinone-Present 69.0 −3.4 2.6 based pigment

[0295] TABLE 7 Fineness Strength Elongation Orientation Density (dtex)(cN/dtex) (%) (× 10⁻³) (g/cm³) Example 40 142 4.78 27.5 168.1 1.38Example 41 174 4.62 29.3 165.4 1.37 Comparative 174 4.50 30.1 165.5 1.37Example 5

1. A polyester polymerization catalyst comprising as a firstmetal-containing component at least one selected from aluminum andcompounds thereof, and at least one coexisting compound selected fromphosphorus compounds represented by the chemical formulae 1 and 2:


2. A polyester produced by using the polyester polymerization catalystof claim
 1. 3. A process for production of polyester in the presence ofthe polyester polymerization catalyst of claim
 1. 4. A fiber produced byusing the polyester of claim
 2. 5. A film produced by using thepolyester of claim
 2. 6. A molded hollow article produced by using thepolyester of claim 2.